mineral
Raw amethyst quartz crystal
Quartz, silicon dioxide (SiO₂), purple variety amethyst
AI-generated identification · may be incorrectMohs hardness 7; translucent purple-to-colorless, vitreous luster, hexagonal crystal structure, and indistinct cleavage with conchoidal fracture. The specimen appears to be a small rough crystal cluster with possible attached matrix or inclusions.
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Physical properties
Mohs hardness 7; translucent purple-to-colorless, vitreous luster, hexagonal crystal structure, and indistinct cleavage with conchoidal fracture. The specimen appears to be a small rough crystal cluster with possible attached matrix or inclusions.
Formation & geological history
Amethyst forms when iron-bearing quartz crystallizes in gas cavities and fractures of volcanic rocks, commonly basalt, with irradiation producing the purple color. Deposits range from ancient Precambrian geodes to younger volcanic formations.
Uses & applications
Used for jewelry, ornaments, geodes, lapidary items, and mineral collecting; small rough fragments have limited industrial value.
Geological facts
Purple color varies with iron content and radiation exposure; heating can turn some amethyst yellow or orange, producing citrine-like material.
Field identification & locations
Identify by purple quartz, glassy luster, hardness sufficient to scratch ordinary glass, and lack of strong cleavage; common sources include Brazil, Uruguay, Zambia, and Mexico. Exact locality cannot be determined from the photograph.
