Allanite-(Ce) is a mineral of the Allanite Group of the Epidote Supergroup, together with 16 other approved minerals (July 2015). Allanite-(Ce) is by far the most common of these minerals, so that the name "allanite" without a Levinson suffix can normally be considered a synonym of allanite-(Ce). There are currently (July 2015) 660 localities listed for allanite-(Ce) in Mindat. In fact, allanite-(Ce) is the most abundant LREE mineral and only monazite-(Ce) is comparable in abundance.
Ideally, the relationship between epidote and allanite-(Ce) can be expressed with the substitution CaFe3+ (epidote) <->REE3+Fe2+, with Ce as the dominant rare earth element (REE). In reality, the chemistry is much more complex, and allanite group minerals can accomodate a wide range of elements. The composition may be variable within individual crystals, and zoned crystals are not uncommon. Historically, the name allanite (and orthite) have been used for any dark, REE-bearing mineral in the epidote supergroup, not always meeting the modern requirement of a ΣREE content larger than 0.5 apfu. References to allanite (orthite) in older literature may therefore be considered epidotes or even clinozoisites in today's literature.
Th and U can replace some of the REE elements, which makes many allanites slightly radioactive. The radioactivity often damages the internal structure of allanite crystals, a process known as metamictization. This process also makes the allanite crystals more susceptible to alteration, typically giving various iron (hydro)oxides as the most common alteration products.
Allanite-(Ce) commonly occurs in a number of geological environments. It is characteristically found as an accessory mineral in igneous rocks such as granite, syenite, granodiorite, monzonite and their pegmatites. It may also occur in larger amounts in some limestone skarns and calc-silicate rocks, as well as in metamorphic rocks that have been derived from igneous rocks, such as gneiss, amphibolite, etc. The diversity of the geological environments is also represented in this article. The largest crystals are found embedded in pegmatites, where crystals more than 1 m long can be found embedded in feldspar. The more "attractive" display specimens are found in skarns, where calcite can be removed to expose free standing crystals. Smaller, more well formed crystals are found in veins associated with quartz or in miarolitic cavities in igneous rock. Perfectly developed crystals are normally only found as micro-crystals in cavities associated with lavas. For such a common mineral, very few fine specimens are known and those that exist are not well known or popular with collectors.
In the 19th century, a number of different names were used to describe what now is called allanite-(Ce), including bucklandite, bagrationite, tautolite, naatelite and cerin. These names usually originated due to minor chemical differences, but were quickly abandoned. Orthite, however, is a synonym that may still be used, even though it was officially abandoned in 1951. Originally, the name allanite was reserved for tabular, non-metamict varieties, and orthite used for metamict prismatic crystals as found in pegmatites. The distinction between the two forms was muddled, and the abandonment of orthite was in no way controversial.
The Mary Kathleen Mine was mined for uranium in two periods from 1956-1963 and 1976-1982. The area was rehabilitated immediately after the second mining period. Uraninite occurred as fine grains (0.01-0.1 mm across) enclosed in allanite in a calc-silicate rock, with coarse grained garnet (grossular-andradite), allanite and clinopyroxene as the main minerals. Hughes and Munroe consider the ratio between the minerals in the ore body to be allanite:apatite:garnet:other minerals 35:10:40:15. If this ratio holds true for the entire ore body, the Mary Kathleen deposit contains more than 3,000 Mt of allanite.
The calc-silicate rock is hosted in the metasedimentary (amphibolite facies metamorphoses) Corella Formation, which consists of feldspar-rich cobble and boulder conglomerate, impure marble, mica schist, quartzite and amphibolite. These rocks have been exposed to two metasomatic events. Hydrothermal fluids related to the second event caused an enrichment of rare earth elements: predominantly Ce and La, and U, Ca, CO2, and H20, and facilitated the conversion of Fe2+ to Fe3+. Derrick (1977) sees this second metasomatic event as responsible for the formation of allanite and garnetification of pre-existing scapolite, as well as the formation of hydrothermal minerals such as prehnite. He further associates this event with the intrusion of rhyolite dykes into the Corella Formation.
Bladed allanite crystals up to 3 cm formed at the contact between massive allanite and calcite. The photos are representative of allanites from this locality. As the mine tailings are rehabilitated, no new specimens will be recovered
Mt Elliot Mine lies in the same geological unit (the Mt Isa inlier) as the Mary Kathleen Mine. Here, allanite-(Ce) can be found as tabular crystals in skarns. The Mt Elliot Mine produces larger and better allanites than the Mary Kathleen Mine, and crystals are generally found associated with other skarn minerals such as scapolite and diopside in a skarn breccia.
The skarn of Mt Elliot is not a typical skarn, in that the host rock is neither carbonate or calcareous, but the result of metasomatic influx of calcium and carbonate. A report prepared by AMC Mining concultants (2012) gives the following sequence of development of the Mt Elliott deposits:
1. Localized pre-skarn quartz veining and silification that predates the end of the ductile deformation.
2. Early potassic alteration of the margins of some amphibolite bodies; perhaps associated with the above event.
3. Albitization (with K-Fe-Mg depletion) of the host rocks. Fracture and fabric controlled sodic alteration, pervasive in the host rocks, with hematite-stained albite, minor scapolite and recrystallized quartz replacing primary lithologies.
4. Predominantly open-space deposition (fracture and fabric controlled) of sodic diopside, actinolite, scapolite, andradite, magnetite, sulphides, apatite, tourmaline and calcite. The diopside and scapolite were deposited earlier than actinolite.
The Parham occurrence was discovered around 1972, and large allanite crystals are the main mineral of interest for collectors. The allanite is rich in both ferrous and ferric iron. An analysis published by Peterson and MacFarlane and republished by Ercit corresponds to a ferri-allanite-(Ce) composition, but work published on Mindat.org by Pavel Kartashov confirms that the large crystals are within the allanite-(Ce) compositional field.
Allanite is found as euhedral crystals up to 10 cm on the edge, and particularly fine large groups of crystals may be seen in the collections of the royal Ontario Museum and Harvard University. Associated minerals include those typical for a Mg skarn assemblage, such as pyroxenes of the diopside-hedenbergite series, calcite, feldspar and minor phlogopite.
Kartashov (2013) is of the opinion that the allanite was formed by a metasomatic event, responsible for the formation of allanite, amphibole, sulphides and albite. This is consistent with the general geology in the area, with rocks belonging to the Frontenac Terrane of the Central Metasedimentary Belt. This Terrane consists of a sequence of marbles, quartzites and quartzofeldspathic gneisses that have been metamorphosed to granulite facies 1170 to 1160 Ma. A metasomatic event may well be related to the intrusion of a series of syenite 1090 to 1070 Ma.
The beryl pit is a complex pegmatite dike which intrudes a granite gneiss. The dike appears to be nearly vertical and strikes approximately 56°N. The wall zone of the dike is comprised of albite-quartz-perthite. The core of the dike at the eastern end is comprised of quartz-albite-biotite micro-pegmatite. Beryl crystals are found along the south side and east end of the core. The west and central part of the core contains a small core of quartz surrounded by a microcline-perthite intermediate zone and a quartz-cleavelandite-tourmaline replacement zone. Allanite-(Ce) occurs in vitreous, black, platy crystals with lyndochite (euxenite-(Y)) in the border zone and in the north wall of the dike. The crystals are fragile and rarely freed from the pegmatite matrix in one piece.
Allanite occurs as black or deep brown tabular crystals measuring up to 8 cm long and up to 2 cm thick, and as clots up to 30 cm across. Allanite was (is?) locally abundant in the pegmatite that mainly consists of microcline and quartz.
The Yates Mine was originally worked for phlogopite (1906 and onwards) and later for fluorite (1943-44). The discovery of uranothorite by Mr. J. M. Yates in 1953 led to the establishment of Yates Uranium Mines, but low uranium grades caused the cessation of exploration a few years later. A new attempt was made in1976, but failed to identify any higher grade uranium ores.
The Yates Mines consist of several calcite vein-dykes of which the Camp Zone and the Matte Zone are the largest. The calcite vein-dykes consist of a pinkish-orange calcite core and bands of calc-silicate rocks and the characteristic large apatite crystals. Allanite-(Ce) occurs as black to brownish black tabular crystals and platy aggregates embedded in calcite and feldspar. Sabina (2007) reports that the crystals reach up to 2.5 cm across, whereas Leavitt(1981) reports crystals up to 10-12 cm.
The Evans-Lou pegmatite, which lies 32 km north of Hull, produced large black allanite crystals up to 60 x 120 cm. (Yes, the crystals are that big but have no terminations to speak of.) When you read descriptions like the one above it is very easy to imagine wonderful specimens that do not exist. Collectors can easily be led astray by the literature.
The Trimouns talc deposit was formed about 300 million years ago by hydrothermal alteration of metapelitic mica schists and carbonates. The hydrothermal fluids were rich in Mg, altering the mica schist to chlorite and the carbonates to talc. Several rare minerals, including REE minerals such as allanite-(Ce) and its Mg-analogue dissakisite-(Ce) are found in vugs in the dolomite.
Allanite-(Ce) and dissakisite-(Ce) occur as individual, short to long prismatic crystals as well as crystal groups. The crystals are rarely longer than 10-12 mm, but crystals up to 4-5 cm are known. The best of these specimens, usually miniatures, are matrix specimens of white massive dolomite. The allanite-(Ce) / dissakisite-(Ce) is sometimes associated with small talc crystals. The French dealer Alain Carion from Paris was responsible for collecting a certain amount of this material.
The relative abundance of these two chemically similar minerals is uncertain, and Hoshino et al. (2008) describe a specimen with zoned crystals. Allanite-(Ce) from here forms only dark colored zones within transparent light colored dissakisite-(Ce) crystals. P. Gatel and P. De Perseval have performed extensive studies on the minerals of Trimouns, and their data may shed more light on the compositional variances of the allanite-(Ce) / dissakisite-(Ce).
As a general rule of thumb, collectors generally label the lighter colored crystals dissakisite-(Ce), and the darker colored specimens allanite-(Ce), but the validity of this assumption has not been confirmed. The photos included from the locality show some of the variances in color of these crystals.
Volcanism in Eifel is part of a series of intra-plate volcanic fields in Central Europe that have been active throughout the Tertiary and Quaternary, and is largely related to rifting of the Rhine Graben and broad uplift of pre-Tertiary basement in the Rhenish Shield. Xenoliths and ejecta from various rocks are common, and host a wide range of different minerals.
Allanite occurs in different associations in the Eifel volcanic field. The most sought after crystals are those up to 1 cm tabular crystals found in miarolitic cavities in sanidinite. Allanite in this paragenesis occurs with sanidine, pyroxene, nosean, apatite, zircon, britholite-(Ce), and pyrochlore.
A second form, normally with smaller, short prismatic to isometric crystals with more crystals faces are found embedded in sanidinite. These crystals only rarely occur as free-standing crystals in small cavities. This allanite occurs with calcite, cancrinite, davyne, nosean, pyrochlore, apatite, magnetite, and rarely nepheline.
In these occurences, allanite is difficult to accurately identify. Not only do the crystals resemble pyroxenes and amphiboles, but also several species in the allanite group have been identified here. The Ce ratio is variable, giving allanite-(Ce) and allanite-(La) as well as ferriallanite-(Ce) and ferriallanite-(La). It appears that the larger, tabular crystals are mostly allanite-(Ce), but insufficient specimens have been analyzed to determine whether there is a relationship between composition, paragenesis and crystal form.
The Stracciacappe caldera belongs to the Sabatini volcanic district, which is part of the perpotassic (potassium rich) Roman magmatic province. The origin of the volcanic activity is debated. The most current interpretation defines the tectonic style as post-collisional, and the associated magmatism as subduction related. The composition of products erupted within the Sabatini volcanic district is considered to be transitional between the mafic Alban Hills leucitites (to the south) and the differentiated Vico and Vulsini suites (to the north). The Sabatini lavas cluster in the tephritic leucite phonolite and tephritic leucitite fields of the Streckeisen "APF" diagram. The volcanic rocks lie on a sedimenlary basement.
Allanite-(Ce) occurs in sanidinite, as small crystals up to a few mm in vugs between sanidine crystals. Both epidote and allanite occur in such vugs, and prismatic crystals of various shades of green have generally been considered epidote and darker (brown to black) tabular crystals have been named allanite-(Ce). Intermediate forms are known, and Mattei and Signoretti (2007) point out that identification based on chemical analyses does not always match those made based on crystal habit and color.
The Tomaino Quarry was opened in 1985 and produces building stone from the Traversella pluton, which is composed mostly of diorite to quartz-diorite with minor monzonite. It also contains mafic cumulates, along with abundant inclusions of both igneous and metasedimentary origin. In addition, various granitic and aplitic veins crosscut the main dioritic body.
Several mineral species are found in the Tomaino Quarry, with prismatic allanite-(Ce) crystals up to 5 cm long as one of the most interesting. The brown allanite-(Ce) occurs with quartz and feldspar in vugs in granitic veins. Allanite-(Ce) is also found in other quarries in the area, including the Vico Cavanese Quarry, where crystals up to 3 cm long were found in a similar vein.
The Seula Mine is a quarry in the pink granite of Baveno, which is a medium-grained granite showing intense, late post-magmatic alteration due to an abundance of fluids in both pneumatolitic and hydrothermal stages. Miarolitic cavities occur isolated in the pink facies of the granite, in pegmatitic veins (where they have irregular shapes), and in aplitic-pegmatitic dikes. These dikes contain granophyric portions characterized by several small cavities in the aplitic units, and large, vertically elongated cavities in the pegmatitic units. These cavities range from 1 cm up to 2–3 m in diameter. All the cavities developed as isolated systems and, in some cases, the largest ones are partially collapsed.
The paragenesis is typical of NYF-pegmatites and developed under magmatic, pneumatolitic and hydrothermal conditions. Allanite-(Ce) seems to have crystallized in vugs in pneumatolitic to high-temperature to medium-temperature hydrothermal conditions.
Allanite-(Ce) is a rare mineral in the Baveno granite. It typically occurs in brownish green to dark brown or black tabular crystals with a strong glassy or resinous luster on fresh surfaces. Grill (1937) described as allanite a black centimetre-sized prismatic crystal, showing a very fresh fracture surface [According to Gramaccioli (2003), crystals of such size have never been found later]. Grill & Scaini (1941) and Nova (1987) described as allanite dark brown to almost black elongated crystals, often grouped into fasciculated or fan-like aggregates, and millimetre-sized spherules.. Allanite-(Ce) is normally associated with epidote, muscovite, fluorite, albite and orthoclase. .
Allanite-(Ce) is found in small quantities, associated with and included in quartz in hydrothermal veins in mica schist. Only the thicker veins (10-15 cm wide) may contain vugs with euhedral quartz and hematite crystals larger than 1 cm. Other associated minerals include chlorite,and minor amounts of apatite, thorite and synchysite.
Allanite-(Ce) is known from several Japanese pegmatites. Unfortunately, there are more chemical analyses available than descriptions of crystals, occurrences and mineral associations. The following summary (Petrov 2015) is based on personal observations in Japanese museums, mineral shops or in the field:
- Ehime Prefecture: Prismatic crystals up to 5 cm long at Mategata.
- Fukushima Prefecture: Many localities in the Ishikawa district, typically about 2 cm in size, although occasionally much bigger. One exceptional crystal at Magaki in this district was nearly 14 cm long.
- Ishikawa Prefecture: On the Noto Peninsula, typically about 6 or 7mm in size, rarely up to 1.5 cm.
- Kyoto Prefecture: On Mt Daimonji in Kyoto city, typically only 8 mm in size but occasionally larger. This was the first locality for allanite in Japan.
- Mie Prefecture: Fukudayama pegmatite, crystals just over 2.5 cm long.
- Osaka Prefecture: Sakaguchi Mine, as anhedral masses up to 15 cm across but no crystals.
The “Mina del Muerto” is a 200 m2 zoned pegmatite with a quartz core, an intermediate zone consisting predominantly of quartz, feldspar (mainly microcline) and mica (biotite) and an outer zone consisting primarily of plagioclase and biotite. The pegmatite is hosted in a gneiss belonging to a metamorphic suite of Grenillian origin. The pegmatite is related to a series of post-peak metamorphosis intrusions.
Allanite-(Ce) is found in the outer zone, associated with the pyrochlore group mineral betafite. Cortez (1981) estimates that the pegmatite contains 176.17 tons of allanite. The allanite is pitch black with a vitreous luster on fresh surfaces, but is often altered to dull brownish masses. The crystals are up to 20 cm long and needle shaped, frequently occurring in fans or rosettes.
During the Carbo-Permian period, southeastern Norway suffered an intracontinental rifting episode, where several stages of magmatism have been recognized. The intrusive rocks were emplaced in Cambro-Silurian sedimentary rocks, and range in composition from monzodiorite and monzonite to syenite and alkali syenite to granite and alkali granite. Although none of these rocks appear to be particularily enriched in REE's, several localities have produced well formed allanite-(Ce) crystals, both in contact skarns between the intrusives and the sedimentary rocks and in miarolitic cavities in syenites.
Exceptionally sharp, platy crystals to about 4 cm have been found in miarolitic cavities in syenites in the hills of the northern part of Oslo. One exceptional crystal (3 cm wide - as far as I recall, Eldjarn (2009)) was found at Grefsenåsen in the mid-19th century (mentioned by Kierulf 1865), and is on display at the Oslo Mineralogical Museum. A photo can be seen here: http://www.mn.uio.no/kjemi/tjenester/kunnskap/periodesystemet/vis.php?e=Ce&vis=alt
Sharp crystals of allanite-(Ce) up to 2 cm, partly with epidote overgrowths, are known from many skarn localities in the Oslo region, e.g. from Hörtekollen in Sylling, Lier, as well as from the Oppsjøen mine, which is a skarn worked for iron ore in the contact between the Drammen granite and sedimentary rocks.
The Slobrekka Quarry is one of several hundred quarries in the Evje / Iveland pegmatite field. Allanite-(Ce) is probably the most common REE mineral in these pegmatites, and Frigstad (in Pedersen (ed.) 2007) considers allanite to be present in almost all of the pegmatites in this area. The pegmatites are enclosed in a 15x30 km metagabbroic complex, and appear to have been emplaced along pre-existing zones of weakness. The pegmatites are enriched in REE elements and are believed to be formed late (~850 MA) in the evolution of the Sveco-Norwegian orogeny at a relatively high temperature (~600o C). Their composition indicates a crustal origin.
Allanite-(Ce) in Slobrekka (like other pegmatites in the area) is metamict due to a small content of radioactive elements. Its color is black with a dull lustre, and is always somewhat altered, showing a crust of yellow alteration products. These are predominantly Fe-oxides, but other minerals such as ancylite-(Ce) and bastnasite-(Ce) can be present. The allanite-(Ce), in some cases, can be completely altered to a yellow-orange powder.
Allanite-(Ce) occurs as long slender crystals up to 50 cm long, often forming fan-like aggregates embedded in feldspar, associated with Y2O3 bearing garnets in the spessartine-almandine series. In some cases, the allanite-(Ce) crystals penetrate rough garnet crystals.
The Hilltveit pegmatite in the Evje/Iveland pegmatite district has perhaps produced the most crystals for collectors. The long prismatic, tabular crystals were known already by Brøgger et al. (1922). Individual crystals are smaller than the ones from Slobrekka and Kåbuland.
Allanite-(Ce) occurs as large columnar crystals embedded in feldspar. The crystals may be more than 1 m long, with a diameter of about 15 cm, and the weight of individual crystals may exceed 100 kg.
The Gloserheia pegmatite is one of the largest in the Froland pegmatite field, one of many pegmatite fields related to the Sweco-Norwegian Kristiansand Bamble thrusting. The Froland field is generally poorer in REE minerals than the nearby Evje/Iveland field.
According to Åmli (1975), allanite-(Ce) is the most abundant rare-earth mineral in the Gloserheia pegmatite. The best crystals occur in what Åmli considers intermediate zone 1, which is closest to the quartz core and is characterized by the presence of large blocky microcline crystals as well as large apatite and allanite crystals.
In this zone, allanite-(Ce) is found as subhedral to anhedral crystals and clusters of crystals of cm to m size. The color is black to dark greenish black. In larger crystals, flesh-red inclusions (mm-sized), which are probably thorite, are observed.
The Lindvikskollen-Kalstad body is the largest pegmatite body in the Kragerø area. It is about 30 m wide and extends 500 m from the very top of Lindvikskollen eastward diagonally down the slope of the hill. It has been quarried extensively all along its length; two of these prospects, the Lindvikskollen and Kalstadgangen Quarries, are famous for their rare minerals.
Allanite-(Ce) is found in large quantities in this pegmatite as brown, shapeless masses and blackish, often tapering prismatic crystals up to at least 10 cm in diameter, and Eldjarn (2009) reports crystals up to 60 cm long. The crystals are embedded in microcline, and allanite-(Ce) probably crystallized at approximately the same time as microcline. Both are covered with a tan alteration product (mainly iron oxides), and are partly metamict.
The Hundholmen pegmatite was mined from 1906 to about 1970 for feldspar, along with some quartz and fluorite. Today, the mine itself is abandoned and opened towards the sea, acting as a harbor for sailboats. The dumps are still accessible, and are known to host a number of very rare minerals, some of them world-class quality. The black allanite-(Ce) specimens from this locality are not world class, but the sharp, well formed crystals up 3 cm that can be found embedded in the pegmatite still form rather attractive specimens of allanite-(Ce).
Allanite is a common mineral in the host granite of the Hundholmen pegmatite, which is a coarse-grained biotite-amphibole alkali granite. It belongs genetically (Muller 2010, 2011) to the Trans-Scandinavian Igneous Belt (TIB), which comprises a giant elongated array of batholiths extending c. 1400 km along the Scandinavian Peninsula from southeastern Sweden to Troms in northwestern Norway. These igneous rocks document a more or less continuous and voluminous magmatic activity between 1850 to 1630 Ma, which developed between the Svecofennian (1920-1790 Ma) and Gothian orogeneses (1640-1520 Ma). Allanite is a very common accessory mineral in these granites in the Tysfjord area, and coarse crystals and irregular masses up to 20 cm are known from several pegmatites in the area.
Gold from Carlés was originally discovered and exploited in Roman times, and has throughout history been mined for gold, copper and arsenic. Since 2000, gold has been mined from the Carlés deposits. The mineralization is related to a granodioritic igneous intrusion into limestones, slates and quartzites, forming skarns and a series of fissures in the sedimentary rocks. These fissures have been important for mineralization of hydrothermal origin. Later igneous dykes up to a few decimeters traverse the intrusion.
These events have led to a complex petrology with several different mineral assemblages. It appears that the allanite-(Ce) is formed by hydrothermal alteration of the skarns along fissures in the rock, where it occurs in a pyroxene, amphibole, magnetite and feldspar assemblage and forms tabular to prismatic crystals up to 1 cm at least.
Allanite-(Ce) has been found as crystals in miarolitic cavities in some of the small epigranitic intrusions in the Cullin complex. Allanite-(Ce) forms very good bladed and tabular dark brown crystals measuring to 4 mm in the Beinn an Dubhaich granites, and as single tabular crystals to 1 mm from the Glas Beinn Mhor and Loch Ainort granites. Allanite-(Ce) has not been seen in crystals in this study from the other granites, but petrological studies confirm the presence of allanite as an accessory mineral in several of these epigranites.
The Pacoima Canyon pegmatite consists of a number of irregular bulging and fingering lenses along a single, nearly horizontal plane. For the most part, the pegmatite consists of very coarse grained, subhedra,l light pinkish-brown perthitic feldspar and white quartz, containing a few large blobs of quartz. There are no evident zonal structures. About 10% of the pegmatite consists of red perthite pods and lenses. It is these lenses that contain the rare minerals of interest to collectors: allanite-(Ce), zircon, apatite and beryl.
Allanite occurs in thin, tabular black crystals, ranging from less than a cm up to 25x40 cm (10x18 in). The best well terminated ones may be in the Los Angeles County Museum collection and are a little over 3 inches long. No alterations are evident and the crystals are only slightly metamict. It is the most abundant of the unusual minerals, but it is still rare to find.
The Trout Creek Pass pegmatite district is located in the Mosquito Range, and it contains numerous granitic pegmatite bodies associated with the Denny Creek granodiorite body. The Denny Creek Granodiorite (1.7 GA) is a cluster of intrusive bodies ranging in composition from quartz monzonite to quartz diorite. In the Trout Creek Pass pegmatite district, the dominant rock type is a foliated biotite-granite, close to quartz monzonite in composition.
The pegmatites range in size from several meters to approximately 85 meters in minimum dimensions. Many are poorly exposed and only four of the larger pegmatites, the Yard, Clora May, Crystal No. 8, and the Tie Gulch pegmatite, exhibit well developed internal zonation.
These four also are characterized by strong REE-mineral enrichments. Allanite-(Ce) and monazite-(Ce) are the dominant LREE-enriched minerals. The allanite-(Ce) is always associated with the microcline perthite of the core of the pegmatites. Allanite-(Ce) typically occurs as anhedral black masses up to 2 cm in size, but long straight crystals up to one cm across and fifteen cm long are reported from the Crystal No. 8 mine.
Allanite is an accessory mineral in several magnetite- and biotite-bearing pegmatite bodies that cut quartz monzonite. Radiating, and often altered, crystals up to 8 inches are known from the Burroughs mine. These crystals are embedded in feldspar and often associated with a euxenite group mineral.
Black glassy crystals as much as 3 inches long are especially well developed in a pegmatite near the head of Maxmilian Gulch in the same area.
Blocky, slightly prismatic crystals of allanite at least 3 cm have been found in the Pikes Peak granites and in particular at Crystal Peak, which is located north of the towns of Florissant and Lake George in both Teller and Park counties. I have never seen a sharp crystal from this locality.
The pegmatites of the Middletown area in Connecticut have been mined for feldspar and muscovite mica since about 1865. The district has been an important producer of feldspar and, to a lesser extent, of sheet mica since 1865 and it has yielded many rare minerals. Well over 400 pegmatites are known to occur within the district and, over the years, a large number of them have been the scene of small mining operations for varying intervals of time.
The Linkput railway cut locality is a small pegmatite vein, no more than 2 ft wide and 50 ft long, that was discovered by Richard Schooner around 1938. Albini (2015) provides the following information: "The site is now a hiking trail, no collecting allowed and the best boulders with allanite are buried under a house's front yard! This cut was blasted for the Airline railroad, at that time the fastest route from New York City to Boston, MA. Richard told me he found the best allanites and other numerous species dumped in a swamp just before the cut on the left side of the cut. In the cut itself, the right side was more productive. There was red fluorite there and helvite among the other numerous species, also bastnaesite crystals (sic) with pyrite xls. ". The association of allanite-(Ce), bastnaesite-(Ce), fluorite, chalcopyrite, pyrite, plagioclase, and quartz makes it unusual for the Middletown pegmatite district.
Allanite-(Ce) is found in sharp terminated crystals crystals up to half an inch in diameter and five or six inches in length, associated with pink fluorite. Massive material also occurs, intergrown with quartz, bastnaesite, pyrite, chalcopyrite, and white to greenish plagioclase (commonly stained brown). The allanite is not very radioactive and XRD revealed that it is non-metamict.
All the Montana localities listed below are located in the Boulder Batolith, which van Laer (2009) describes as follows:
"The Boulder Batholith of Montana is a late Cretaceous-early Tertiary aged granitic intrusion located in southwest Montana, occupying the Butte copper district and extending northward to Helena, Montana. Compositionally, it is largely a quartz monzonite, but is slightly more mafic in places, and also leaning towards true granite in other areas. Its overall size is about forty miles long and twenty miles across; it contacts metasediments in some places, and is covered by unconsolidated sediments in other places. Throughout southwest Montana, other similar granitic intrusions of identical age and/or composition are found. It is largely equigranular granite but contains larger phenocrysts of k-spar locally and in some areas xenoliths are quite common.
The Boulder Batholith is the host rock for the greater Butte copper-lead-zinc and molybdenum deposits, along with numerous, lesser deposits of tungsten, gold, silver, and other base metals. Locally, aplites and pegmatites are common; these are generally interior-type pegmatites, that is, they are found within the granite mass rather than adjacent to it (exterior pegmatites). The pegmatites are locally vuggy and may contain good examples of crystalline granite-druse minerals, such as smoky quartz, microcline, albite, epidote, tourmaline, titanite (sphene), axinite, and a host of lesser accessory minerals."
Allanite is a common accessory mineral in several of the monzogranite and granodirite rocks that form the Bouder Batholite. Table 1 of du Bray et al. (2012) gives an overview of the various units and which ones that carry allanite-(Ce). Larger allanite crystals up to minimum 4 in. can be found embedded in pegmatites related to the allanite bearing intrusives. Allanite-(Ce) may also be found associated with smoky quartz and epidote in vugs. These are rarer, smaller and more well formed than the crystals embedded in pegmatite rock.
Numerous aplites, grano-aplites and alaskaites are found throughout the area, and locally these bodies grade into coarse pegmatites. These are graphic granite pegmatites, marking the transition between fine-grained aplite and pegmatite and/or cavities.
Allanites originate from cavities in a pegmatite associated with feldspar and minor titanite, and allanite-(Ce) is a rare mineral in these vugs.
"Allanite-(Ce) very rarely grows in pockets; the one pictured above was one of many found in a local pegmatite a few years ago, by the same collector who found the blue cleavelandite, so he is not revealing the exact locality. Now that some time has passed, I may be able to get that information, since recently the site has been discovered and worked by others. Crystals from this locality were all miniatures, plus a couple of thumbnails; up to about 1-1/2 inch in length, and distinctly terminated and twinned. Local allanites are often associated with epidote, and the two are often grown together, with grey allanite cores and outer zones of green epidote. The epidote will almost always coat the allanite when grown in a pocket, and epidote-free allanites are almost exclusively "frozen" in pegmatite matrix. I worked a remote, large pegmatite back in the 1980s for huge smoky quartz crystals that also produced allanites up to four inches long and weighing hundreds of grams. These were merely sections of what had been much larger crystals, and I will add the exact details of these to my article". (William C. van Laer )
This allanite-(Ce) is also originates from an occurrence related to the Boulder Batolith.
In the Red Rock prospect area, aplite-pegmatite dikes cut quartz diorite that has been intruded by quartz monzonite. Eight allanite pegmatite segregations occur in a large aplite-pegmatite at the Red Rock prospect. The allanite predominantly occurs as anhedral crystals up to 6 cm long and 1 cm wide. Crystals with developed crystal phases are rarer. Due to a small (0.5%wt) U3O8 content, the allanite is metamict, and aften altered. Allanite is found in a matrix of quartz, albite and microcline. The allanite forms from 5 to 30% of the pegmatite segregations.
The Estrella claim is located on the south side of the El Capitan Mountains. The locality is better known for its Japan law twins of smoky quartz, but it also produces some sharp, fairly lustrous allanite crystals to about 3 cm. Most of the specimens from here are single crystals that make good thumbnail specimens.
There are several REE-bearing vein and breccia deposits similar to the Estrella claim in the Capitan Mountains, where allanite-(Ce) occurs with quartz. They occur as tabular bodies, narrow lenses, and breccia zones along faults, fractures,and shearzones hosted in trachyte, alaskite, nepheline syenite, syenite,and alkali granite. The deposits vary from a few feet to 1,000 ft long and from less than one inch to 10 ft wide.
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Mindat locality pages, mineral pages and photo captions.
Reviewed July 2015: Becky Coulson
Ideally, the relationship between epidote and allanite-(Ce) can be expressed with the substitution CaFe3+ (epidote) <->REE3+Fe2+, with Ce as the dominant rare earth element (REE). In reality, the chemistry is much more complex, and allanite group minerals can accomodate a wide range of elements. The composition may be variable within individual crystals, and zoned crystals are not uncommon. Historically, the name allanite (and orthite) have been used for any dark, REE-bearing mineral in the epidote supergroup, not always meeting the modern requirement of a ΣREE content larger than 0.5 apfu. References to allanite (orthite) in older literature may therefore be considered epidotes or even clinozoisites in today's literature.
Th and U can replace some of the REE elements, which makes many allanites slightly radioactive. The radioactivity often damages the internal structure of allanite crystals, a process known as metamictization. This process also makes the allanite crystals more susceptible to alteration, typically giving various iron (hydro)oxides as the most common alteration products.
Allanite-(Ce) commonly occurs in a number of geological environments. It is characteristically found as an accessory mineral in igneous rocks such as granite, syenite, granodiorite, monzonite and their pegmatites. It may also occur in larger amounts in some limestone skarns and calc-silicate rocks, as well as in metamorphic rocks that have been derived from igneous rocks, such as gneiss, amphibolite, etc. The diversity of the geological environments is also represented in this article. The largest crystals are found embedded in pegmatites, where crystals more than 1 m long can be found embedded in feldspar. The more "attractive" display specimens are found in skarns, where calcite can be removed to expose free standing crystals. Smaller, more well formed crystals are found in veins associated with quartz or in miarolitic cavities in igneous rock. Perfectly developed crystals are normally only found as micro-crystals in cavities associated with lavas. For such a common mineral, very few fine specimens are known and those that exist are not well known or popular with collectors.
In the 19th century, a number of different names were used to describe what now is called allanite-(Ce), including bucklandite, bagrationite, tautolite, naatelite and cerin. These names usually originated due to minor chemical differences, but were quickly abandoned. Orthite, however, is a synonym that may still be used, even though it was officially abandoned in 1951. Originally, the name allanite was reserved for tabular, non-metamict varieties, and orthite used for metamict prismatic crystals as found in pegmatites. The distinction between the two forms was muddled, and the abandonment of orthite was in no way controversial.
Australia
Mary Kathleen Mine, Mary Kathleen district, Rosebud Station, Cloncurry Shire, Queensland, Australia
The Mary Kathleen Mine was mined for uranium in two periods from 1956-1963 and 1976-1982. The area was rehabilitated immediately after the second mining period. Uraninite occurred as fine grains (0.01-0.1 mm across) enclosed in allanite in a calc-silicate rock, with coarse grained garnet (grossular-andradite), allanite and clinopyroxene as the main minerals. Hughes and Munroe consider the ratio between the minerals in the ore body to be allanite:apatite:garnet:other minerals 35:10:40:15. If this ratio holds true for the entire ore body, the Mary Kathleen deposit contains more than 3,000 Mt of allanite.
The calc-silicate rock is hosted in the metasedimentary (amphibolite facies metamorphoses) Corella Formation, which consists of feldspar-rich cobble and boulder conglomerate, impure marble, mica schist, quartzite and amphibolite. These rocks have been exposed to two metasomatic events. Hydrothermal fluids related to the second event caused an enrichment of rare earth elements: predominantly Ce and La, and U, Ca, CO2, and H20, and facilitated the conversion of Fe2+ to Fe3+. Derrick (1977) sees this second metasomatic event as responsible for the formation of allanite and garnetification of pre-existing scapolite, as well as the formation of hydrothermal minerals such as prehnite. He further associates this event with the intrusion of rhyolite dykes into the Corella Formation.
Bladed allanite crystals up to 3 cm formed at the contact between massive allanite and calcite. The photos are representative of allanites from this locality. As the mine tailings are rehabilitated, no new specimens will be recovered
Mount Elliott Mine (Mount Elliott Copper Mine), Selwyn District, Cloncurry Shire, Queensland, Australia
Mt Elliot Mine lies in the same geological unit (the Mt Isa inlier) as the Mary Kathleen Mine. Here, allanite-(Ce) can be found as tabular crystals in skarns. The Mt Elliot Mine produces larger and better allanites than the Mary Kathleen Mine, and crystals are generally found associated with other skarn minerals such as scapolite and diopside in a skarn breccia.
The skarn of Mt Elliot is not a typical skarn, in that the host rock is neither carbonate or calcareous, but the result of metasomatic influx of calcium and carbonate. A report prepared by AMC Mining concultants (2012) gives the following sequence of development of the Mt Elliott deposits:
1. Localized pre-skarn quartz veining and silification that predates the end of the ductile deformation.
2. Early potassic alteration of the margins of some amphibolite bodies; perhaps associated with the above event.
3. Albitization (with K-Fe-Mg depletion) of the host rocks. Fracture and fabric controlled sodic alteration, pervasive in the host rocks, with hematite-stained albite, minor scapolite and recrystallized quartz replacing primary lithologies.
4. Predominantly open-space deposition (fracture and fabric controlled) of sodic diopside, actinolite, scapolite, andradite, magnetite, sulphides, apatite, tourmaline and calcite. The diopside and scapolite were deposited earlier than actinolite.
Canada
Parham occurrence, Olden Township, Frontenac County, Ontario, Canada
The Parham occurrence was discovered around 1972, and large allanite crystals are the main mineral of interest for collectors. The allanite is rich in both ferrous and ferric iron. An analysis published by Peterson and MacFarlane and republished by Ercit corresponds to a ferri-allanite-(Ce) composition, but work published on Mindat.org by Pavel Kartashov confirms that the large crystals are within the allanite-(Ce) compositional field.
Allanite is found as euhedral crystals up to 10 cm on the edge, and particularly fine large groups of crystals may be seen in the collections of the royal Ontario Museum and Harvard University. Associated minerals include those typical for a Mg skarn assemblage, such as pyroxenes of the diopside-hedenbergite series, calcite, feldspar and minor phlogopite.
Kartashov (2013) is of the opinion that the allanite was formed by a metasomatic event, responsible for the formation of allanite, amphibole, sulphides and albite. This is consistent with the general geology in the area, with rocks belonging to the Frontenac Terrane of the Central Metasedimentary Belt. This Terrane consists of a sequence of marbles, quartzites and quartzofeldspathic gneisses that have been metamorphosed to granulite facies 1170 to 1160 Ma. A metasomatic event may well be related to the intrusion of a series of syenite 1090 to 1070 Ma.
Beryl Pit, Quadeville area, Lyndoch Township, Brudenell-Lyndoch-and-Raglan, Renfrew County, Ontario, Canada
The beryl pit is a complex pegmatite dike which intrudes a granite gneiss. The dike appears to be nearly vertical and strikes approximately 56°N. The wall zone of the dike is comprised of albite-quartz-perthite. The core of the dike at the eastern end is comprised of quartz-albite-biotite micro-pegmatite. Beryl crystals are found along the south side and east end of the core. The west and central part of the core contains a small core of quartz surrounded by a microcline-perthite intermediate zone and a quartz-cleavelandite-tourmaline replacement zone. Allanite-(Ce) occurs in vitreous, black, platy crystals with lyndochite (euxenite-(Y)) in the border zone and in the north wall of the dike. The crystals are fragile and rarely freed from the pegmatite matrix in one piece.
Lac Baude allanite Locality, Mékinac RCM, Mauricie, Québec, Canada
Allanite occurs as black or deep brown tabular crystals measuring up to 8 cm long and up to 2 cm thick, and as clots up to 30 cm across. Allanite was (is?) locally abundant in the pegmatite that mainly consists of microcline and quartz.
Yates Mine, Otter Lake, Pontiac RCM, Outaouais, Québec, Canada
The Yates Mine was originally worked for phlogopite (1906 and onwards) and later for fluorite (1943-44). The discovery of uranothorite by Mr. J. M. Yates in 1953 led to the establishment of Yates Uranium Mines, but low uranium grades caused the cessation of exploration a few years later. A new attempt was made in1976, but failed to identify any higher grade uranium ores.
The Yates Mines consist of several calcite vein-dykes of which the Camp Zone and the Matte Zone are the largest. The calcite vein-dykes consist of a pinkish-orange calcite core and bands of calc-silicate rocks and the characteristic large apatite crystals. Allanite-(Ce) occurs as black to brownish black tabular crystals and platy aggregates embedded in calcite and feldspar. Sabina (2007) reports that the crystals reach up to 2.5 cm across, whereas Leavitt(1981) reports crystals up to 10-12 cm.
Evans-Lou Mine, Lake Saint-Pierre, Saint-Pierre-de-Wakefield, Val-des-Monts, Les Collines-de-l'Outaouais RCM, Outaouais, Québec, Canada
The Evans-Lou pegmatite, which lies 32 km north of Hull, produced large black allanite crystals up to 60 x 120 cm. (Yes, the crystals are that big but have no terminations to speak of.) When you read descriptions like the one above it is very easy to imagine wonderful specimens that do not exist. Collectors can easily be led astray by the literature.
France,
Trimouns Talc Mine, Luzenac, Foix, Ariège, Occitanie, France
The Trimouns talc deposit was formed about 300 million years ago by hydrothermal alteration of metapelitic mica schists and carbonates. The hydrothermal fluids were rich in Mg, altering the mica schist to chlorite and the carbonates to talc. Several rare minerals, including REE minerals such as allanite-(Ce) and its Mg-analogue dissakisite-(Ce) are found in vugs in the dolomite.
Allanite-(Ce) and dissakisite-(Ce) occur as individual, short to long prismatic crystals as well as crystal groups. The crystals are rarely longer than 10-12 mm, but crystals up to 4-5 cm are known. The best of these specimens, usually miniatures, are matrix specimens of white massive dolomite. The allanite-(Ce) / dissakisite-(Ce) is sometimes associated with small talc crystals. The French dealer Alain Carion from Paris was responsible for collecting a certain amount of this material.
The relative abundance of these two chemically similar minerals is uncertain, and Hoshino et al. (2008) describe a specimen with zoned crystals. Allanite-(Ce) from here forms only dark colored zones within transparent light colored dissakisite-(Ce) crystals. P. Gatel and P. De Perseval have performed extensive studies on the minerals of Trimouns, and their data may shed more light on the compositional variances of the allanite-(Ce) / dissakisite-(Ce).
As a general rule of thumb, collectors generally label the lighter colored crystals dissakisite-(Ce), and the darker colored specimens allanite-(Ce), but the validity of this assumption has not been confirmed. The photos included from the locality show some of the variances in color of these crystals.
Germany
Laacher See Volcanic Complex, Germany
Volcanism in Eifel is part of a series of intra-plate volcanic fields in Central Europe that have been active throughout the Tertiary and Quaternary, and is largely related to rifting of the Rhine Graben and broad uplift of pre-Tertiary basement in the Rhenish Shield. Xenoliths and ejecta from various rocks are common, and host a wide range of different minerals.
Allanite occurs in different associations in the Eifel volcanic field. The most sought after crystals are those up to 1 cm tabular crystals found in miarolitic cavities in sanidinite. Allanite in this paragenesis occurs with sanidine, pyroxene, nosean, apatite, zircon, britholite-(Ce), and pyrochlore.
A second form, normally with smaller, short prismatic to isometric crystals with more crystals faces are found embedded in sanidinite. These crystals only rarely occur as free-standing crystals in small cavities. This allanite occurs with calcite, cancrinite, davyne, nosean, pyrochlore, apatite, magnetite, and rarely nepheline.
In these occurences, allanite is difficult to accurately identify. Not only do the crystals resemble pyroxenes and amphiboles, but also several species in the allanite group have been identified here. The Ce ratio is variable, giving allanite-(Ce) and allanite-(La) as well as ferriallanite-(Ce) and ferriallanite-(La). It appears that the larger, tabular crystals are mostly allanite-(Ce), but insufficient specimens have been analyzed to determine whether there is a relationship between composition, paragenesis and crystal form.
Italy
Stracciacappe caldera, Metropolitan City of Rome Capital, Lazio, Italy
The Stracciacappe caldera belongs to the Sabatini volcanic district, which is part of the perpotassic (potassium rich) Roman magmatic province. The origin of the volcanic activity is debated. The most current interpretation defines the tectonic style as post-collisional, and the associated magmatism as subduction related. The composition of products erupted within the Sabatini volcanic district is considered to be transitional between the mafic Alban Hills leucitites (to the south) and the differentiated Vico and Vulsini suites (to the north). The Sabatini lavas cluster in the tephritic leucite phonolite and tephritic leucitite fields of the Streckeisen "APF" diagram. The volcanic rocks lie on a sedimenlary basement.
Allanite-(Ce) occurs in sanidinite, as small crystals up to a few mm in vugs between sanidine crystals. Both epidote and allanite occur in such vugs, and prismatic crystals of various shades of green have generally been considered epidote and darker (brown to black) tabular crystals have been named allanite-(Ce). Intermediate forms are known, and Mattei and Signoretti (2007) point out that identification based on chemical analyses does not always match those made based on crystal habit and color.
Las Superiore Quarry, Traversella, Metropolitan City of Turin, Piedmont, Italy
The Tomaino Quarry was opened in 1985 and produces building stone from the Traversella pluton, which is composed mostly of diorite to quartz-diorite with minor monzonite. It also contains mafic cumulates, along with abundant inclusions of both igneous and metasedimentary origin. In addition, various granitic and aplitic veins crosscut the main dioritic body.
Several mineral species are found in the Tomaino Quarry, with prismatic allanite-(Ce) crystals up to 5 cm long as one of the most interesting. The brown allanite-(Ce) occurs with quartz and feldspar in vugs in granitic veins. Allanite-(Ce) is also found in other quarries in the area, including the Vico Cavanese Quarry, where crystals up to 3 cm long were found in a similar vein.
Seula mine, Mount Camoscio, Oltrefiume, Baveno, Verbano-Cusio-Ossola Province, Piedmont, Italy
The Seula Mine is a quarry in the pink granite of Baveno, which is a medium-grained granite showing intense, late post-magmatic alteration due to an abundance of fluids in both pneumatolitic and hydrothermal stages. Miarolitic cavities occur isolated in the pink facies of the granite, in pegmatitic veins (where they have irregular shapes), and in aplitic-pegmatitic dikes. These dikes contain granophyric portions characterized by several small cavities in the aplitic units, and large, vertically elongated cavities in the pegmatitic units. These cavities range from 1 cm up to 2–3 m in diameter. All the cavities developed as isolated systems and, in some cases, the largest ones are partially collapsed.
The paragenesis is typical of NYF-pegmatites and developed under magmatic, pneumatolitic and hydrothermal conditions. Allanite-(Ce) seems to have crystallized in vugs in pneumatolitic to high-temperature to medium-temperature hydrothermal conditions.
Allanite-(Ce) is a rare mineral in the Baveno granite. It typically occurs in brownish green to dark brown or black tabular crystals with a strong glassy or resinous luster on fresh surfaces. Grill (1937) described as allanite a black centimetre-sized prismatic crystal, showing a very fresh fracture surface [According to Gramaccioli (2003), crystals of such size have never been found later]. Grill & Scaini (1941) and Nova (1987) described as allanite dark brown to almost black elongated crystals, often grouped into fasciculated or fan-like aggregates, and millimetre-sized spherules.. Allanite-(Ce) is normally associated with epidote, muscovite, fluorite, albite and orthoclase. .
Acqua Bianca valley, Gorfigliano, Minucciano, Lucca Province, Tuscany, Italy
Allanite-(Ce) is found in small quantities, associated with and included in quartz in hydrothermal veins in mica schist. Only the thicker veins (10-15 cm wide) may contain vugs with euhedral quartz and hematite crystals larger than 1 cm. Other associated minerals include chlorite,and minor amounts of apatite, thorite and synchysite.
Japan
Fukudayama, Hakusan, Tsu City, Mie Prefecture, Japan
Allanite-(Ce) is known from several Japanese pegmatites. Unfortunately, there are more chemical analyses available than descriptions of crystals, occurrences and mineral associations. The following summary (Petrov 2015) is based on personal observations in Japanese museums, mineral shops or in the field:
- Ehime Prefecture: Prismatic crystals up to 5 cm long at Mategata.
- Fukushima Prefecture: Many localities in the Ishikawa district, typically about 2 cm in size, although occasionally much bigger. One exceptional crystal at Magaki in this district was nearly 14 cm long.
- Ishikawa Prefecture: On the Noto Peninsula, typically about 6 or 7mm in size, rarely up to 1.5 cm.
- Kyoto Prefecture: On Mt Daimonji in Kyoto city, typically only 8 mm in size but occasionally larger. This was the first locality for allanite in Japan.
- Mie Prefecture: Fukudayama pegmatite, crystals just over 2.5 cm long.
- Osaka Prefecture: Sakaguchi Mine, as anhedral masses up to 15 cm across but no crystals.
Mexico
Muerto Mine, San Francisco Telixtlahuaca, San Francisco Telixtlahuaca Municipality, Oaxaca, Mexico
The “Mina del Muerto” is a 200 m2 zoned pegmatite with a quartz core, an intermediate zone consisting predominantly of quartz, feldspar (mainly microcline) and mica (biotite) and an outer zone consisting primarily of plagioclase and biotite. The pegmatite is hosted in a gneiss belonging to a metamorphic suite of Grenillian origin. The pegmatite is related to a series of post-peak metamorphosis intrusions.
Allanite-(Ce) is found in the outer zone, associated with the pyrochlore group mineral betafite. Cortez (1981) estimates that the pegmatite contains 176.17 tons of allanite. The allanite is pitch black with a vitreous luster on fresh surfaces, but is often altered to dull brownish masses. The crystals are up to 20 cm long and needle shaped, frequently occurring in fans or rosettes.
Norway
Oppsjøen Mine, Oppsjø, Dikemark, Asker, Viken, Norway
During the Carbo-Permian period, southeastern Norway suffered an intracontinental rifting episode, where several stages of magmatism have been recognized. The intrusive rocks were emplaced in Cambro-Silurian sedimentary rocks, and range in composition from monzodiorite and monzonite to syenite and alkali syenite to granite and alkali granite. Although none of these rocks appear to be particularily enriched in REE's, several localities have produced well formed allanite-(Ce) crystals, both in contact skarns between the intrusives and the sedimentary rocks and in miarolitic cavities in syenites.
Exceptionally sharp, platy crystals to about 4 cm have been found in miarolitic cavities in syenites in the hills of the northern part of Oslo. One exceptional crystal (3 cm wide - as far as I recall, Eldjarn (2009)) was found at Grefsenåsen in the mid-19th century (mentioned by Kierulf 1865), and is on display at the Oslo Mineralogical Museum. A photo can be seen here: http://www.mn.uio.no/kjemi/tjenester/kunnskap/periodesystemet/vis.php?e=Ce&vis=alt
Sharp crystals of allanite-(Ce) up to 2 cm, partly with epidote overgrowths, are known from many skarn localities in the Oslo region, e.g. from Hörtekollen in Sylling, Lier, as well as from the Oppsjøen mine, which is a skarn worked for iron ore in the contact between the Drammen granite and sedimentary rocks.
Frikstad 07 Feldspar Quarry, Frikstad, Iveland, Agder, Norway
The Slobrekka Quarry is one of several hundred quarries in the Evje / Iveland pegmatite field. Allanite-(Ce) is probably the most common REE mineral in these pegmatites, and Frigstad (in Pedersen (ed.) 2007) considers allanite to be present in almost all of the pegmatites in this area. The pegmatites are enclosed in a 15x30 km metagabbroic complex, and appear to have been emplaced along pre-existing zones of weakness. The pegmatites are enriched in REE elements and are believed to be formed late (~850 MA) in the evolution of the Sveco-Norwegian orogeny at a relatively high temperature (~600o C). Their composition indicates a crustal origin.
Allanite-(Ce) in Slobrekka (like other pegmatites in the area) is metamict due to a small content of radioactive elements. Its color is black with a dull lustre, and is always somewhat altered, showing a crust of yellow alteration products. These are predominantly Fe-oxides, but other minerals such as ancylite-(Ce) and bastnasite-(Ce) can be present. The allanite-(Ce), in some cases, can be completely altered to a yellow-orange powder.
Allanite-(Ce) occurs as long slender crystals up to 50 cm long, often forming fan-like aggregates embedded in feldspar, associated with Y2O3 bearing garnets in the spessartine-almandine series. In some cases, the allanite-(Ce) crystals penetrate rough garnet crystals.
Hiltveit 02 Feldspar Quarry (Feitedalen), Hiltveit, Iveland, Agder, Norway
The Hilltveit pegmatite in the Evje/Iveland pegmatite district has perhaps produced the most crystals for collectors. The long prismatic, tabular crystals were known already by Brøgger et al. (1922). Individual crystals are smaller than the ones from Slobrekka and Kåbuland.
Kåbuland 01 Feldspar Quarry (Amerika), Kåbuland, Iveland, Agder, Norway
Allanite-(Ce) occurs as large columnar crystals embedded in feldspar. The crystals may be more than 1 m long, with a diameter of about 15 cm, and the weight of individual crystals may exceed 100 kg.
Gloserheia, Froland, Agder, Norway
The Gloserheia pegmatite is one of the largest in the Froland pegmatite field, one of many pegmatite fields related to the Sweco-Norwegian Kristiansand Bamble thrusting. The Froland field is generally poorer in REE minerals than the nearby Evje/Iveland field.
According to Åmli (1975), allanite-(Ce) is the most abundant rare-earth mineral in the Gloserheia pegmatite. The best crystals occur in what Åmli considers intermediate zone 1, which is closest to the quartz core and is characterized by the presence of large blocky microcline crystals as well as large apatite and allanite crystals.
In this zone, allanite-(Ce) is found as subhedral to anhedral crystals and clusters of crystals of cm to m size. The color is black to dark greenish black. In larger crystals, flesh-red inclusions (mm-sized), which are probably thorite, are observed.
Lindvikskollen Quarry, Lindvikskollen-Kalstadgangen pegmatite, Kragerø, Telemark, Norway
The Lindvikskollen-Kalstad body is the largest pegmatite body in the Kragerø area. It is about 30 m wide and extends 500 m from the very top of Lindvikskollen eastward diagonally down the slope of the hill. It has been quarried extensively all along its length; two of these prospects, the Lindvikskollen and Kalstadgangen Quarries, are famous for their rare minerals.
Allanite-(Ce) is found in large quantities in this pegmatite as brown, shapeless masses and blackish, often tapering prismatic crystals up to at least 10 cm in diameter, and Eldjarn (2009) reports crystals up to 60 cm long. The crystals are embedded in microcline, and allanite-(Ce) probably crystallized at approximately the same time as microcline. Both are covered with a tan alteration product (mainly iron oxides), and are partly metamict.
Hundholmen, Narvik, Nordland, Norway
The Hundholmen pegmatite was mined from 1906 to about 1970 for feldspar, along with some quartz and fluorite. Today, the mine itself is abandoned and opened towards the sea, acting as a harbor for sailboats. The dumps are still accessible, and are known to host a number of very rare minerals, some of them world-class quality. The black allanite-(Ce) specimens from this locality are not world class, but the sharp, well formed crystals up 3 cm that can be found embedded in the pegmatite still form rather attractive specimens of allanite-(Ce).
Allanite is a common mineral in the host granite of the Hundholmen pegmatite, which is a coarse-grained biotite-amphibole alkali granite. It belongs genetically (Muller 2010, 2011) to the Trans-Scandinavian Igneous Belt (TIB), which comprises a giant elongated array of batholiths extending c. 1400 km along the Scandinavian Peninsula from southeastern Sweden to Troms in northwestern Norway. These igneous rocks document a more or less continuous and voluminous magmatic activity between 1850 to 1630 Ma, which developed between the Svecofennian (1920-1790 Ma) and Gothian orogeneses (1640-1520 Ma). Allanite is a very common accessory mineral in these granites in the Tysfjord area, and coarse crystals and irregular masses up to 20 cm are known from several pegmatites in the area.
Spain
Carlés Mine, Carlés, Salas, Asturias, Spain
Gold from Carlés was originally discovered and exploited in Roman times, and has throughout history been mined for gold, copper and arsenic. Since 2000, gold has been mined from the Carlés deposits. The mineralization is related to a granodioritic igneous intrusion into limestones, slates and quartzites, forming skarns and a series of fissures in the sedimentary rocks. These fissures have been important for mineralization of hydrothermal origin. Later igneous dykes up to a few decimeters traverse the intrusion.
These events have led to a complex petrology with several different mineral assemblages. It appears that the allanite-(Ce) is formed by hydrothermal alteration of the skarns along fissures in the rock, where it occurs in a pyroxene, amphibole, magnetite and feldspar assemblage and forms tabular to prismatic crystals up to 1 cm at least.
UK
Eas a Bradain, Luib, Isle of Skye, Eilean á Chèo, Highland, Scotland, UK
Allanite-(Ce) has been found as crystals in miarolitic cavities in some of the small epigranitic intrusions in the Cullin complex. Allanite-(Ce) forms very good bladed and tabular dark brown crystals measuring to 4 mm in the Beinn an Dubhaich granites, and as single tabular crystals to 1 mm from the Glas Beinn Mhor and Loch Ainort granites. Allanite-(Ce) has not been seen in crystals in this study from the other granites, but petrological studies confirm the presence of allanite as an accessory mineral in several of these epigranites.
USA
Pacoima Canyon pegmatite locality (Pacoima Canyon Allanite pegmatite; Allanite locality), Pacoima Canyon, Los Angeles County, California, USA
The Pacoima Canyon pegmatite consists of a number of irregular bulging and fingering lenses along a single, nearly horizontal plane. For the most part, the pegmatite consists of very coarse grained, subhedra,l light pinkish-brown perthitic feldspar and white quartz, containing a few large blobs of quartz. There are no evident zonal structures. About 10% of the pegmatite consists of red perthite pods and lenses. It is these lenses that contain the rare minerals of interest to collectors: allanite-(Ce), zircon, apatite and beryl.
Allanite occurs in thin, tabular black crystals, ranging from less than a cm up to 25x40 cm (10x18 in). The best well terminated ones may be in the Los Angeles County Museum collection and are a little over 3 inches long. No alterations are evident and the crystals are only slightly metamict. It is the most abundant of the unusual minerals, but it is still rare to find.
Tie Gulch Pegmatite, Buena Vista, Chaffee County, Colorado, USA
The Trout Creek Pass pegmatite district is located in the Mosquito Range, and it contains numerous granitic pegmatite bodies associated with the Denny Creek granodiorite body. The Denny Creek Granodiorite (1.7 GA) is a cluster of intrusive bodies ranging in composition from quartz monzonite to quartz diorite. In the Trout Creek Pass pegmatite district, the dominant rock type is a foliated biotite-granite, close to quartz monzonite in composition.
The pegmatites range in size from several meters to approximately 85 meters in minimum dimensions. Many are poorly exposed and only four of the larger pegmatites, the Yard, Clora May, Crystal No. 8, and the Tie Gulch pegmatite, exhibit well developed internal zonation.
These four also are characterized by strong REE-mineral enrichments. Allanite-(Ce) and monazite-(Ce) are the dominant LREE-enriched minerals. The allanite-(Ce) is always associated with the microcline perthite of the core of the pegmatites. Allanite-(Ce) typically occurs as anhedral black masses up to 2 cm in size, but long straight crystals up to one cm across and fifteen cm long are reported from the Crystal No. 8 mine.
Burroughs Mine (Traut-Rudin-Anderson Pegmatite; Sunrise Peak Mine), Clear Creek pegmatite Province, Jefferson County, Colorado, USA
Allanite is an accessory mineral in several magnetite- and biotite-bearing pegmatite bodies that cut quartz monzonite. Radiating, and often altered, crystals up to 8 inches are known from the Burroughs mine. These crystals are embedded in feldspar and often associated with a euxenite group mineral.
Black glassy crystals as much as 3 inches long are especially well developed in a pegmatite near the head of Maxmilian Gulch in the same area.
Blocky, slightly prismatic crystals of allanite at least 3 cm have been found in the Pikes Peak granites and in particular at Crystal Peak, which is located north of the towns of Florissant and Lake George in both Teller and Park counties. I have never seen a sharp crystal from this locality.
Linkpot cut, Airline Railroad, East Hampton (Chatham), Middlesex County, Connecticut, USA
The pegmatites of the Middletown area in Connecticut have been mined for feldspar and muscovite mica since about 1865. The district has been an important producer of feldspar and, to a lesser extent, of sheet mica since 1865 and it has yielded many rare minerals. Well over 400 pegmatites are known to occur within the district and, over the years, a large number of them have been the scene of small mining operations for varying intervals of time.
The Linkput railway cut locality is a small pegmatite vein, no more than 2 ft wide and 50 ft long, that was discovered by Richard Schooner around 1938. Albini (2015) provides the following information: "The site is now a hiking trail, no collecting allowed and the best boulders with allanite are buried under a house's front yard! This cut was blasted for the Airline railroad, at that time the fastest route from New York City to Boston, MA. Richard told me he found the best allanites and other numerous species dumped in a swamp just before the cut on the left side of the cut. In the cut itself, the right side was more productive. There was red fluorite there and helvite among the other numerous species, also bastnaesite crystals (sic) with pyrite xls. ". The association of allanite-(Ce), bastnaesite-(Ce), fluorite, chalcopyrite, pyrite, plagioclase, and quartz makes it unusual for the Middletown pegmatite district.
Allanite-(Ce) is found in sharp terminated crystals crystals up to half an inch in diameter and five or six inches in length, associated with pink fluorite. Massive material also occurs, intergrown with quartz, bastnaesite, pyrite, chalcopyrite, and white to greenish plagioclase (commonly stained brown). The allanite is not very radioactive and XRD revealed that it is non-metamict.
Rader Creek, Boulder Batholith, Jefferson County, Montana, USA
All the Montana localities listed below are located in the Boulder Batolith, which van Laer (2009) describes as follows:
"The Boulder Batholith of Montana is a late Cretaceous-early Tertiary aged granitic intrusion located in southwest Montana, occupying the Butte copper district and extending northward to Helena, Montana. Compositionally, it is largely a quartz monzonite, but is slightly more mafic in places, and also leaning towards true granite in other areas. Its overall size is about forty miles long and twenty miles across; it contacts metasediments in some places, and is covered by unconsolidated sediments in other places. Throughout southwest Montana, other similar granitic intrusions of identical age and/or composition are found. It is largely equigranular granite but contains larger phenocrysts of k-spar locally and in some areas xenoliths are quite common.
The Boulder Batholith is the host rock for the greater Butte copper-lead-zinc and molybdenum deposits, along with numerous, lesser deposits of tungsten, gold, silver, and other base metals. Locally, aplites and pegmatites are common; these are generally interior-type pegmatites, that is, they are found within the granite mass rather than adjacent to it (exterior pegmatites). The pegmatites are locally vuggy and may contain good examples of crystalline granite-druse minerals, such as smoky quartz, microcline, albite, epidote, tourmaline, titanite (sphene), axinite, and a host of lesser accessory minerals."
Allanite is a common accessory mineral in several of the monzogranite and granodirite rocks that form the Bouder Batholite. Table 1 of du Bray et al. (2012) gives an overview of the various units and which ones that carry allanite-(Ce). Larger allanite crystals up to minimum 4 in. can be found embedded in pegmatites related to the allanite bearing intrusives. Allanite-(Ce) may also be found associated with smoky quartz and epidote in vugs. These are rarer, smaller and more well formed than the crystals embedded in pegmatite rock.
Homestake Pass, Boulder Batholith, Jefferson County, Montana, USA
Numerous aplites, grano-aplites and alaskaites are found throughout the area, and locally these bodies grade into coarse pegmatites. These are graphic granite pegmatites, marking the transition between fine-grained aplite and pegmatite and/or cavities.
Allanites originate from cavities in a pegmatite associated with feldspar and minor titanite, and allanite-(Ce) is a rare mineral in these vugs.
Silver Bow County, Montana, USA
"Allanite-(Ce) very rarely grows in pockets; the one pictured above was one of many found in a local pegmatite a few years ago, by the same collector who found the blue cleavelandite, so he is not revealing the exact locality. Now that some time has passed, I may be able to get that information, since recently the site has been discovered and worked by others. Crystals from this locality were all miniatures, plus a couple of thumbnails; up to about 1-1/2 inch in length, and distinctly terminated and twinned. Local allanites are often associated with epidote, and the two are often grown together, with grey allanite cores and outer zones of green epidote. The epidote will almost always coat the allanite when grown in a pocket, and epidote-free allanites are almost exclusively "frozen" in pegmatite matrix. I worked a remote, large pegmatite back in the 1980s for huge smoky quartz crystals that also produced allanites up to four inches long and weighing hundreds of grams. These were merely sections of what had been much larger crystals, and I will add the exact details of these to my article". (William C. van Laer )
Butte Mining District (Summit Valley Mining District), Silver Bow County, Montana, USA
This allanite-(Ce) is also originates from an occurrence related to the Boulder Batolith.
Red Rock prospect, Stateline Peak Mining District, Fort Sage Mountains, Washoe County, Nevada, USA
In the Red Rock prospect area, aplite-pegmatite dikes cut quartz diorite that has been intruded by quartz monzonite. Eight allanite pegmatite segregations occur in a large aplite-pegmatite at the Red Rock prospect. The allanite predominantly occurs as anhedral crystals up to 6 cm long and 1 cm wide. Crystals with developed crystal phases are rarer. Due to a small (0.5%wt) U3O8 content, the allanite is metamict, and aften altered. Allanite is found in a matrix of quartz, albite and microcline. The allanite forms from 5 to 30% of the pegmatite segregations.
Mina Tiro Estrella, Capitan Mining District, Capitan Mountains, Lincoln County, New Mexico, USA
The Estrella claim is located on the south side of the El Capitan Mountains. The locality is better known for its Japan law twins of smoky quartz, but it also produces some sharp, fairly lustrous allanite crystals to about 3 cm. Most of the specimens from here are single crystals that make good thumbnail specimens.
There are several REE-bearing vein and breccia deposits similar to the Estrella claim in the Capitan Mountains, where allanite-(Ce) occurs with quartz. They occur as tabular bodies, narrow lenses, and breccia zones along faults, fractures,and shearzones hosted in trachyte, alaskite, nepheline syenite, syenite,and alkali granite. The deposits vary from a few feet to 1,000 ft long and from less than one inch to 10 ft wide.
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If I can steal a picture from Rudy.... Here is an allanite from a place not far from me, the Burroughs Mine. This locality is on private property and was only mined for a few years. Actually a few of REE pegmatites along the front range of Colorado have allanite. I haven't visited many of them however, so don't know what the crystals are like from those.
"A 16.2x2.1x1.5cm; 81.4gm, crystal. Specimen has been reassembled. Allanite at this locality all occurs already fractured in place. the crystals are easily removed from pegmatite wall with fingers. Natural rehealing is visible at fractures as well as alterations on crystal surface. Rudy Bolona collection; collected Sept. 1, 2007."
Burroughs Mine (Traut-Rudin-Anderson Pegmatite; Sunrise Peak Mine), Clear Creek pegmatite Province, Jefferson Co., Colorado, USA, 16.2cm wide
"A 16.2x2.1x1.5cm; 81.4gm, crystal. Specimen has been reassembled. Allanite at this locality all occurs already fractured in place. the crystals are easily removed from pegmatite wall with fingers. Natural rehealing is visible at fractures as well as alterations on crystal surface. Rudy Bolona collection; collected Sept. 1, 2007."
In den Dellen quarries, Mendig, Mendig, Mayen-Koblenz, Rhineland-Palatinate, Germany