mineral
Amethyst
Quartz, SiO₂; purple coloration is associated with trace iron and natural irradiation.
AI-generated identification · may be incorrectMohs hardness 7; purple, translucent, with a vitreous luster and hexagonal crystal structure. The small specimen appears tumbled or polished, so cleavage is not visible; quartz has no cleavage and conchoidal fracture.
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Physical properties
Mohs hardness 7; purple, translucent, with a vitreous luster and hexagonal crystal structure. The small specimen appears tumbled or polished, so cleavage is not visible; quartz has no cleavage and conchoidal fracture.
Formation & geological history
Amethyst forms as silica-rich fluids deposit quartz in cavities, commonly in volcanic rocks. Its age varies by deposit, often spanning millions to hundreds of millions of years.
Uses & applications
Used in jewelry, ornaments, and mineral collections; lower-grade material is also used for decorative objects.
Geological facts
Amethyst is the purple variety of quartz, and heating can turn some material yellow-orange or greenish.
Field identification & locations
Identify by its purple color, glassy luster, and hardness; common sources include Brazil, Uruguay, Zambia, and Russia. The image shows a small, polished purple piece.
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Granite
Granite (Phaneritic intrusive igneous rock)
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