gemstone

Amethyst (rough crystal fragment)

Purple quartz, silicon dioxide (SiO₂), colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent purple color with vitreous luster and conchoidal fracture. Trigonal crystal structure; quartz has indistinct cleavage and specific gravity about 2.65.

Identified August 17, 2026More gemstone →

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Physical properties

Hardness 7 Mohs; translucent purple color with vitreous luster and conchoidal fracture. Trigonal crystal structure; quartz has indistinct cleavage and specific gravity about 2.65.

Formation & geological history

Forms when silica-rich fluids fill cavities in volcanic rocks, especially basaltic lava flows, where quartz crystals grow slowly in geodes. Most deposits are Cenozoic to Mesozoic, though quartz formation spans much of geological time.

Uses & applications

Used for jewelry, carvings, ornamental specimens, and metaphysical collecting; lower-grade material is used as decorative aggregate. This small rough piece has modest specimen value.

Geological facts

Purple color ranges from pale lilac to deep violet and can fade with prolonged heat or sunlight. Amethyst is February’s birthstone and the traditional gem for the sixth wedding anniversary.

Field identification & locations

Identify it by purple quartz color, glassy luster, hardness, and lack of obvious cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, Namibia, and Mexico.