For the mineral analyses, a scanning electron microscope JEOL JSM-5600 combined with an energy dispersive X-ray microanalysis system Oxford Link Isis 300 system were used. X-ray powder diffraction measurements were obtained using a SIEMENS D-500 diffractometer with Cu tube and Co filter. Materials and MethodsĪnalytical methods included optical and electron microscopy, X-ray powder diffraction studies, and electron microprobe analyses, in the Section of Mineralogy-Petrology at University of Athens and at the Institute of Mineralogy and Petrology, University of Hamburg. The occurrences of gemstones in Greece are presented in Figure 1 and Figure 2 and described with respect to their geological framework and the conditions of their formation. The aim of this work is to review all available information on the geology, mineralogy, geochemistry, and fluid characteristics involved in the formation of various gemstones in Greece. The gemstones of Greece are set within diverse geological settings, the study of which will increase our knowledge on the conditions necessary for their crystallization and concentration into economically-viable deposits. Exploration work in Greece over the last three decades has resulted in the discovery of new occurrences of mineral megacrysts many of them being gem-quality. Known gem material included rubies from Xanthi, sapphire and beryl from Naxos Island, red-colored spessartine from Paros Island, smithsonite from the oxidation zone of the Lavrion mines, and the green quartz variety (prase) from the Serifos skarn. Traditionally, Greece has not been regarded as a source country for gemstones. Future modern exploration methods combined with gemological investigations (such as treatment and faceting of selected stones), are necessary in order to obtain a better knowledge of the gemstone potential of Greece for its possible exploitation. Coloration in the studied material is either due to various chromophore trace elements present in the crystal structure, or due to inclusions of other mineral phases. The supergene oxidation zone of the Lavrion deposit hosts gem-quality smithsonite and azurite. The Tertiary (and Mesozoic) magmatic-hydrothermal environments provide gem-quality sapphire, beryl, garnet, vesuvianite, epidote, fluorite, and SiO 2 varieties. In crystalline rocks, gemstones are related to both regional metamorphic-metasomatic processes (e.g., gem corundums, Mn-andalusite, thulite/clinothulite, spessartine, titanite, jadeite), and to the formation of late alpine-type fissures, such as, for example, quartz, albite, adularia and titanite. In the Hellenides Orogen, minerals of various gem quality occur in various rock types from mainly four tectono-metamorphic units, the Rhodope, Pelagonian, and the Attico-Cycladic massifs, and the Phyllites-Quartzites unit of Crete Island.
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