Quartz

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A sharp glassy gem crystal of quartz. In good condition, the quality is excellent.The Penas Blancas Mine, located in the Boyaca Department of Colombia within the western emerald belt of the Eastern Cordillera, is a historic emerald-mining concession that has been worked at intervals since the Spanish colonial period. Geologically, unlike most global beryllium deposits found in pegmatites, Colombian emerald deposits are hosted in Lower Cretaceous carbonate-bearing black shales and limestones. Hydrothermal sedimentary brines circulated through these strata along faults, leaching essential elements and depositing emeralds within calcite, pyrite, and dolomite veins. Mineralogically, the mine is noted for producing fine, slightly bluish-green emerald crystals, often accompanied by distinct quartz veining, pyrite, and rare-earth carbonates, alongside rough material exhibiting secondary chemical etching known locally as cascocho.