mineral
Tumbled amethyst
Amethyst, purple variety of quartz (SiO₂)
AI-generated identification · may be incorrectMohs hardness 7; purple to violet with a vitreous luster and hexagonal crystal structure. The specimen is polished, so natural crystal faces and cleavage are not visible; quartz has no cleavage and conchoidal fracture.
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Physical properties
Mohs hardness 7; purple to violet with a vitreous luster and hexagonal crystal structure. The specimen is polished, so natural crystal faces and cleavage are not visible; quartz has no cleavage and conchoidal fracture.
Formation & geological history
Amethyst forms as silica-rich fluids crystallize in cavities, commonly in volcanic rocks; deposits range from geologically recent to hundreds of millions of years old.
Uses & applications
Used in jewelry, ornaments, and mineral collections; tumbled pieces are commonly sold as inexpensive decorative stones.
Geological facts
Its purple color is associated with trace iron and natural irradiation; heating can alter it toward yellow-orange citrine hues.
Field identification & locations
The polished oval shape and purple coloration are consistent with tumbled amethyst, though a photo cannot confirm identity; common sources include Brazil, Uruguay, and Zambia.
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