Evia Geology
The south and central Evia Island, belongs to the Attico-Cycladic Massif and has a complex geological, magmatic and tectono-metamorphic history that documents the convergence between the Apulian microplate and the Eurasian continent (Ring et al. 2007; Xypolias et al., 2012). In Attica, and Evia, the lowermost, Basal Unit (BU) represents a late Triassic to late Cretaceous platform of neritic meta-dolomites and -flysch. The BU is exposed in the Ymittos, Penteli and Almyropotamos tectonic windows which are mainly composed of a thick (c. 2000 m) succession of Triassic to Middle Eocene marbles with thin metapelite intercalations (Ring et al., 2007). Above the marbles there is a c. 1500 m thick late Eocene to Oligocene metaflysch that contains abundant olistoliths (Dubois and Bignot, 1979). The overlying Cycladic Blueschist Unit (CBU) represents a succession of a late Paleozoic-Mesozoic continental margin, which comprises a Pre-Alpidic anatectic basement overlain by a volcano-sedimentary sequence (Van Hinsbergen and Schmid 2012). The CBU in Evia comprises two tectonic nappes: i) A lower marble-schist, the Styra Nappe which represents a passive-margin sequence consisting of a thick (c.1000 m) succession of metabauxite-bearing marbles, quartzites and metapelites, with metabasic rocks and serpentinite lenses at its base. ii) An upper meta-ophiolite bearing sequence, the Ochi Nappe, which contains blocks of meta-gabbro, -wehrlite and -basalt in a serpentinite matrix together with meta-rhyolite, piemontite-rich -chert, quartzite and carbonate-rich schist (Katsikatsos, 1991; Katzir et al., 2000). The Uppermost Cycladic unit (UCU) is rarely exposed in either Attica or Evia, and mainly comprises Permian to Mesozoic sedimentary rocks, ofiolites and late Cretaceous greenschist-to-amphibolite facies rocks (Papanikolaou, 2009). The tectonic juxtaposition of UCU with the underlying CBU was possibly accomplished in early Miocene (Bröcker and Franz, 1998).

Introduction
The alpinotype quartz, in the Attico-Cycladic Massif, are mainly reported from Attica (e.g., Stamata, Marathon and Penteli, Attica, Kilias et al., 2004) and Evia Island (e.g., Krieza-Koskina, Karystos, Voudouris and Katerinopoulos, 2004; Voudouris et al., 2004; Voudouris et al., 2005; Tsolakos et al., 2008; Maneta and Voudouris, 2010; Voudouris and Maneta, 2010; Ottens and Voudouris, 2018). Furthermore, alpinotype quartz are reported (Papanikolaou, 1978; Vandenberg and Lister, 1996; Voudouris et al., 2004; Voudouris et al., 2019, Voudouris et al., 2019) from the Islands of Ios (e.g., Mylopotas), Andros (e.g., Petalo), Syros (Kampos), Samos (e.g., Ampelos) and Ikaria (e.g., Pounta).

The Krieza-Koskina Alpinotype Quartz veins
The Krieza-Koskina area in Evia (central Greece) consists of blue- and greenschists, marbles, amphibolites and orthogneisses (Katzir et al., 2000; Shaked et al., 2000). Alpinotype quartz crystals have been grown in quartz veins that fill in sigmoidal fissures, or segregations, comprising the assemblage quartz and feldspar (mostly albite and adularia). These quartz crystals are translucent and their colors vary from white to smoky and colorless. They expose a wide variety of crystal forms, including typical prismatic, gwindel and scepter growth crystals and/or faden and flatten. They also include chlorite phantoms, as well as actinolite, epidote, feldspars, i.e., albite and adularia, rutile, anhydrite-gypsum and hematite (var. iron rose) inclusions. Furthermore, window structures are often developed on the faces of some colorless to white prismatic and Tessin habited crystals and elestial quartz forms. Alpinotype crystals containing chlorite phantoms, or with growth inhibition and mechanical interference and dark smoky quartz crystals are also present in Krieza-Koskina. According to Voudouris et al., (2004, 2019) the mineralogy and crystal morphology and habit of quartz from Krieza-Koskina area in Evia Island and Stamata and Penteli in Attica is almost identical. Kilias et al. (2004) reported that the Attica alpine quartz veins, based on fluid inclusions study, were formed at T ≈ 170º to 240ºC, salinities of ≤ ~ 23 wt. % NaCl equivalent and depth of ~ 5.8 km. Voudouris et al. (2005) reported that the alpine quartz veins at Krieza-Koskina in Evia were formed at T ≈ 140º to 210ºC, salinities of ≤ ~ 22 wt. % NaCl equivalent, although their formation may have started at T ≈ 350ºC and pressure of ~ 3.5 kbar, i.e., at depth of ~ 13 km. Both these alpine veins were deposited from fluids underwent phase separation (at T ~ 200ºC for the Attica alpine veins and T ~ 150ºC for the Evia veins) and then mixed/contaminated by meteoric waters.
In the last two years of 2020-2021, many new veins were discovered by Spiros Kardakaris, researcher and prospector, which produced quartz crystals of exceptional quality and sizes ranging from mm to 18 cm.
In May of 2021 a unique find of alpine quartz-albite vein was located, which consists of colorless quartz crystals with mainly hematite (var. iron rose) and albite and minor chlorite, actinolite and epidote inclusions. These specimens display scepter forms with chlorite phantoms, prasem-like chlorite-actinolite inclusions quartz and on top colorless quartz with hematite (var. iron rose) inclusions or/and around the perimeter of the main crystals. Moreover, there is an occurrence of gemmy and white feldspars, i.e., albite or/and adularia up to 8 cm crystals and up to 1 m clusters with chlorite, actinolite and epidote inclusions and on top of these, there are high quality hematite (var. iron rose) up to 6 cm crystals. The albite crystals display characteristic Carlsbad and multiple twinning and zoned margins. Furthermore, there are quartz specimens which have an uncommon sheeted-like growth, indicating their internal onion lamellar structure, which is a common feature of scepters and skeleton quartz. Also, there are bi-color quartz crystals, white to clear and green (chlorite and actinolite inclusions).
Inside the colorless alpinotype quartz due to epitaxial overgrowth stalagmitic-to-stylolite-like crystals of hematite (var. iron rose) occur as clusters, or beige-to-cream inclusions, with lengths up to 5 cm. Some from these distinctive hematite inclusions are perimorphosed by albite that forms white clusters inclusions and/or are developed as stalagmitic-to-stylolite-like crystals due to growth via an epitaxial mechanism with albite. In some occasions these hematite clusters, or inclusions alter to colloform goethite and limonite.

Conclusions
This new quartz-albite alpine vein comprises the assemblage: quartz + albite + chlorite + actinolite + epidote + hematite + adularia. It was formed in three evolutional stages that overgrow each other with an epitaxial habit. The first stage consists of prasem-like quartz with chlorite, actinolite and epidote, whilst the second stage, replacing the latter, comprises hematite (var. iron rose) and albite and/or adularia. The third stage composes of colorless quartz containing mainly hematite and albite stalactic-like inclusions and minor chlorite, actinolite and goethite inclusions. For the alpine quartz veins at Krieza-Koskina we record a decrease of the fO2 values of the metamorphic fluids from logfO2 ≈ - 28 (T ≈ 350ºC) to ≈ - 39 (T ≈ 200ºC) and then to ≈ - 45 (T ≈ 150ºC) which most probably relates to the precipitation of the epitaxial hematite (var. iron rose).
The paragenesis of inclusions of this alpinotype quartz crystal and the major mineral paragenesis have been analyzed by the Raman method in the Lab of National and Technical University of Athens.
These discoveries are made by the team of Crystal Prospectors, by Spiros Kardakaris, with absolute love for Greece and the science of geology and the enrichment through donations of the country's museums and in particular the new National Geological Museum of Greece (N.G.M.G.) of H.S.G.M.E., in order to ensure the national geological heritage for future generations.
This locality was known to collectors for having produced alpine-type minerals, but no specimens of this quality had been found in many years. This find may be considered the most important recent alpinotype quartz find in Greece with unique and worldwide quality.

Photos: George Kafantaris

More information and photos:
https://www.crystalprospectors.com/post/%CE%B5%CF%80%CE%B9%CF%83%CE%BA%CF%8C%CF%80%CE%B7%CF%83%CE%B7-%CE%BD%CE%AD%CE%B1%CF%82-%CF%83%CF%80%CE%AC%CE%BD%CE%B9%CE%B1%CF%82-%CE%B1%CE%BD%CE%B1%CE%BA%CE%AC%CE%BB%CF%85%CF%88%CE%B7%CF%82-%CF%87%CE%B1%CE%BB%CE%B1%CE%B6%CE%B9%CE%B1%CE%BA%CF%8E%CE%BD-%CF%86%CE%BB%CE%B5%CE%B2%CF%8E%CE%BD-2021-2022


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