 | | Report (issue) |
| Contents 4 Map: Notable Opal Localities 50 BY BRUCE PAUL GABER 6 The Opal Enigma: Science, History...and Pins Afire: Play of Color in Opal BY MAX WEIBEL Sparkling Opal in Ancient Bones: Precious Relics...vibrant with opal pattern and color. In this extreme close-up of a Lightning Ridge black opal, the field...approximately 3 mm wide. Opal courtesy Jenni Brammall BY ALEX RITCHIE 52 An Opal Glossary of Terms BY...BY SI AND ANN FRAZIER BY PETER HUBER 64 Opal from Mexico: Unsurpassed Fire BY JURGEN SCHUTZ 18 Perfect |
 | | Book |
| 1982 Jules Roger Sauer ” Foreword For years Brazil has been the major producer of colored stones in...metamorphic rocks, the variety of gem deposits in Brazil is almost infinite. In addition to the mineral...assemblage one might expect from pegmatite dikes, Brazil also produces a very significant output of diamonds...written in English, and beautifully illustrated. “Brazil, Paradise of Gemstones’, by Jules Roger Sauer,...Grande do Norte, in 1953, the precious opals of Pedro I] in Piaui, in 1960, and a turquoise vein near |
 | | Journal (article/letter/editorial) |
| observed. The outer part of the scattering curves of opal-CT and microcrystalline quartz deviates from Porod’s...in opal-CT (Jones and Segnit 1971; Graetsch et al. 1994). The difference between opal-C and opal-CT appears...exploratory and does not use this technique. A precious opal of gem quality has been used at the Institut Laue-Langevin...for many years for calibration purposes since this opal yields well-resolved diffraction maxima at very...Coober Pedy, South Australia Boi Morto, Piaui, Brazil Boi Morto, Piaui, Brazil Gran Canaria, Spain Rio Grande |
 | | Journal (article/letter/editorial) |
| article, we summarize six deposits: diaspore, fire opal, blue chalcedony, amethyst, smoky quartz, and agate...amethyst include Uruguay, Brazil, Zambia, Mozambique, Mexico, and Siberia. Fire opal is commercially available...from Mexico and Brazil. Smoky quartz is available from numerous sources including Brazil, Madagascar, Russia...agates is geographically widespread and includes Brazil, Mexico, Botswana, Australia, Argentina, and the...entrance to the Kucuk Camiliktepe diasporitic bauxite mine, which produced gem diaspore (zultanite) crystals |
 | | Journal (issue) |
| Da~c~ Ca 1000.00 10.00 ·' 00.00 (Fe2 OJ /Ti02) <II C . .. 10.00 - ~DO ell 0 o D 100.00 1000...from East Australia and Pailin, PaiIin, using Fe, Ii Ti concentrations, concentrations, however, is is...essentiallyfall fallinto into2 2 show only negligible Ii «0.005% Ti022). ). Ti (<0.005% distinct groups. The...only om from rich 'basaltic' type corundum from and Ii-rich Ti-rich type has 0.1-0.2% Ii0 Ti022.• Many Barrington...2% Fe around 0.07% 0.07% Ti0 Ti02 (Table (TableII).II). around 2 the Anakie and New England fields range |
 | | Journal (issue) |
| recently. A good distantvision reading indicated opal, but our customer didn't think it could be, such...nondestructive a n d the material, which was probably opal, was frangible to say the least. A matching density...comparison stone established the stone to be opal. * * * Another opal, which caused me a lot of trouble customerwise...customerwise, not gemmologically, was a black opal purchased as such, mounted in a ring a n d offered for...found the opal colour lipped slightly into the potch and again where potch merged into opal colour. This |
 | | Journal (issue) |
| Pavilion None to weak bluish white (sw) ' $7ki ii , -+.-, -'-.A ' * Moderate to strong bluish white...being i n the Rio Grande do Sul mining area of Brazil, close to the Uruguay border, or in northern Uruguay...specimens of sectored amethyst from Minas Gerais, Brazil, which were also obtained from the Gemological...heat-treating sectored amethyst from Minas Gerais, Brazil, in either one of two ways: (1)a medium heating...heating and irradiating sectored amethyst from Brazil; 12 mm across. Since the sectored amethysts tested |
 | | Journal (issue) |
| in Russia each weighing approximately 1 ct. Table II. The spectrum of the ordinary ray (o) is characterized...! 500 700 800 1 600 Wavelength (ran) Table II: UV/VIS absorption maxima and assignments Absorption...alkali ions and the weaker band is caused by type-II water molecules which are bound to alkali ions. ...the XXI International Gemmological Conference, Brazil 1987 Dillon, S., 1981. Gem news: synthetic red...inclusions in Nacken synthetic emeralds 495481 In ~ I ii ~ ~~ B B 49 6 B b B c I I I I I I |
 | | Journal (issue) |
| moving products from mine to consumer. The main cover image was taken at the AnahÌ mine in Bolivia, a major...of the company (Even-Zohar, 2007). Because of the mine closures, De Beers’s market share by volume fell...pink diamonds (0.51 and 0.55 ct) from the Argyle mine in Australia were part of the 2007 Argyle pink diamonds...had acquired a 32.8% interest in Angola’s Catoca mine in the early 1990s. Commissioned in 1997, Catoca...mining giant Rio Tinto opened Canada’s second diamond mine, Diavik, with 60% ownership. Rio Tinto had established |
 | | Journal (issue) |
| flux blue, pink and orange sapphires; synthetic opal in a variety of body colours and patterns to their...reading taken on the apex of of the cap with a Duplex II refractometer refractometer revealed a value of of...explanation is that, as with some turquoise and opal, the finished piece may merely have been too thin...large rubellite crystals were found in the pegmatite mine at Sakangyi. Furthermore, Bauer (Spencer transi...wairodi (both Malabar. & Singhal); kattöga. "Pseudo-Opal". Commentary The meagre descriptions above are augmented |
 | | Journal (issue) |
| during its brief tenure in the USSR after World War II. In the authors' opinion, the consistency of these...Vaults before they were damaged during World War II. Photo 0 The Worshipful Company of Goldsmiths, London...a ribbon-like design set with rows of small old-mine-cut diamonds that sweeps up from the sides and culminates...(figure 91. THE COUNTRY OF ORIGIN DEBATE: INDIA OR BRAZIL? Tillander (1988) states that "without doubt the...GEMOLOGY Winter 1990 255 in a few publications Brazil has been suggested." The latter suggestion probably |
 | | Journal (issue) |
| method on the apex of the cabochon with a Duplex II refractometer and white light source. Optic Character:...based on Philemon Holland's translation of 1601). II: "... [Median smaragdi] appear naturally of a green...natural emeralds from two localities, the USSR and Brazil USSR (URALS): Single stone approx. 1ct £15 per...four stones approx. 1ct total weight £15 the set Brazil: Single heart-shaped approx. O.25ct £12 per stone...(c) Stones with 'dead milk' (i) "dead milk'area (ii) blue area * ** *** X Y ND Fe Ti V Minor Trace |
 | | Book |
| opalescence the milky effect seen in common opal and in some precious opal. Not to be confused with play of colour...itself - olivine may be altered to serpentine and opal or agate may be deposited in cavities. Contact metamorphism...by hot mineral-bearing solutions which may allow opal and other gem materials to form. 1.1 FORMATION...the stone came from - sometimes down to the actual mine. Today it is commonplace to see in sale catalogues...indicating a carbonaceous material. Emeralds from Brazil are usually full of thin liquid films and there |
| | Book |
| opalescence the milky effect seen in common opal and in some precious opal. Not to be confused with play of colour...itself - olivine may be altered to serpentine and opal or agate may be deposited in cavities. Contact metamorphism...by hot mineral-bearing solutions which may allow opal and other gem materials to form. 1.1 FORMATION...stone came from — some¬ times down to the actual mine. Today it is commonplace to see in sale catalogues...indicating a carbonaceous material. Emeralds from Brazil are usually full of thin liquid films and there |
 | | Book |
| Onicolo Onyx 158 Sardonyx 202 Turquoise 224 Opal 159 Scapolite 202 Uvarovite 231 Orthoclase...minerals were densely con- centrated. This type of mine was very at- tractive, since it avoided the need...materials Quartz crystals from Corinto, Minas Gerais, Brazil. Height: 15 cm. Sorbonne collection using gravity...Washing diamond-bearing gravel in Minas Gerais, Brazil. Photo: tals of such minerals as quartz, fluorite...and a jeweler might then speak of a ‘root’ as Brazil Length: 9 cm. K. Proctor collection, United States |
 | | Book |
| -~~1---------- 1960-2015 by Thom.as P. Moore Volume II I-Z Published by the Mineralogical Record, Inc....Springfield show ( 1995: 582). Madawaska [Faraday] mine near Bow Lake, Hastings County. Some of the world's...property of, the old Madawaska uranium mine (called the Faraday mine before 1964). The mineral assemblage...Trimble and Cowgill, 1977). LATINAMERICA BRAZIL Jacupiranga mine, Sao Paulo. Among the crystallized minerals...Oblast. Alpine-type clefts in the famous Dodo quartz mine commonly contain ilmenite, occurring as lustrous |
 | | Journal (article/letter/editorial) |
| Nontronite Nosean Nsutite Nyerereite Olivenite Olivine Opal Orpiment Otavite Paladium Paragonite Paralstonite...hanging wall. During a subsequent mining period, the mine was re-opened to recover sideritic parts of the...you look for a mine look near a mine”. This includes the imperative “if you look for a mine look for smelting...gold-bearing quartz veins in the southern Para State, Brazil (Angelica et al., 1997). Chromium muscovite named...conglomerate-hosted U deposits of the Randtype at Jacobina, Brazil (pers. com. P. Laznicka). Chromium-bearing garnet |
| | Journal (article/letter/editorial) |
| Nontronite Nosean Nsutite Nyerereite Olivenite Olivine Opal Orpiment Otavite Paladium Paragonite Paralstonite...hanging wall. During a subsequent mining period, the mine was re-opened to recover sideritic parts of the...you look for a mine look near a mine”. This includes the imperative “if you look for a mine look for smelting...gold-bearing quartz veins in the southern Para State, Brazil (Angelica et al., 1997). Chromium muscovite named...conglomerate-hosted U deposits of the Randtype at Jacobina, Brazil (pers. com. P. Laznicka). Chromium-bearing garnet |
Boi Morto mine, Pedro II, Piauí, Brazil