mineral

Amethyst cluster

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

AI-generated identification · may be incorrect

Violet, transparent-to-translucent, glassy luster with hexagonal prismatic crystals and uneven fracture; Mohs hardness 7, specific gravity about 2.65, and no cleavage. The pale blue-white coating/base may be quartz or associated matrix.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, especially basalt, where quartz crystals grow over millions of years; individual deposits range from Paleozoic to Cenozoic in age. Common sources include Brazil, Uruguay, Zambia, and Mexico.

Uses & applications

Used as an ornamental and collectible specimen, in jewelry, carvings, and lapidary work; crushed quartz also has industrial uses, though fine clusters are valued primarily for display.

Geological facts

Amethyst is the purple member of the quartz family and is February’s birthstone. Heating can turn it yellow-orange, producing citrine-like material.

Field identification & locations

Identify it by its purple hexagonal quartz crystals, hardness sufficient to scratch glass, and lack of cleavage; beware dyed quartz or glass imitations. Natural clusters commonly retain a crystalline drusy base and color zoning.