mineral
Quartz (Yellow Quartz / Citrine / Calcite)
Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)
Hardness 7 on Mohs scale (if Quartz) or 3 (if Calcite); pale yellow to cream color; vitreous to greasy luster; trigonal crystal system; conchoidal fracture (Quartz) or rhombohedral cleavage (Calcite); specific gravity 2.65.
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Physical properties
Hardness 7 on Mohs scale (if Quartz) or 3 (if Calcite); pale yellow to cream color; vitreous to greasy luster; trigonal crystal system; conchoidal fracture (Quartz) or rhombohedral cleavage (Calcite); specific gravity 2.65.
Formation & geological history
Forms in hydrothermal veins, pegmatites, or sedimentary environment via precipitation from aqueous solutions containing silica or calcium carbonate.
Uses & applications
Used widely for mineral collections, tumbling, decorative stones, costume jewelry, and crystal healing practices.
Geological facts
Yellow quartz is often naturally iron-stained quartz, or heat-treated amethyst sold as citrine. Calcite can easily be distinguished by reacts and effervescing with dilute acid.
Field identification & locations
Identify in the field by checking hardness with a steel blade or copper coin; quartz will scratch glass while calcite will be scratched by steel. Found in pegmatite pockets, limestone beds, and stream gravels globally.
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