gemstone

Amethyst quartz fragment

Quartz, silicon dioxide (SiO₂), purple variety colored primarily by iron impurities and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with vitreous luster, likely irregularly fractured rather than showing clear cleavage. Quartz is trigonal and has specific gravity about 2.65.

Identified August 18, 2026More gemstone →

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Physical properties

Mohs hardness 7; translucent purple with vitreous luster, likely irregularly fractured rather than showing clear cleavage. Quartz is trigonal and has specific gravity about 2.65.

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, commonly alongside agate and calcite; individual crystals may form over millions of years, often in Cretaceous to younger volcanic environments.

Uses & applications

Used as a jewelry and ornamental gemstone, lapidary material, and collectible mineral; small rough fragments typically have modest value.

Geological facts

Purple color intensity varies with iron content, irradiation, and heating; heat treatment can turn amethyst yellow or orange, producing citrine-like material.

Field identification & locations

Identify by its purple color, glassy luster, lack of cleavage, and ability to scratch ordinary glass. Common sources include Brazil, Uruguay, Zambia, and amethyst-bearing volcanic geodes worldwide.