mineral

Amethyst (purple quartz)

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

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, white streak, conchoidal fracture, and no cleavage; purple coloration ranges from pale lilac to deep violet. The specimen appears rough and translucent, though its small size and lighting limit certainty.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, commonly alongside basalt or agate; many commercial deposits formed in Mesozoic volcanic provinces. Quartz crystallization may occur millions to hundreds of millions of years after host-rock formation.

Uses & applications

Used as a semiprecious gemstone, ornamental stone, beads, carvings, and mineral specimens. Small rough pieces generally have modest value unless color, transparency, and crystal form are exceptional.

Geological facts

Amethyst is the traditional February birthstone and the purple variety of quartz. Heating can turn it yellow or orange, producing citrine-like material.

Field identification & locations

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