mineral

Tumbled amethyst

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

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with vitreous luster, conchoidal fracture, and no cleavage. Crystalline quartz structure; the smooth rounded shape is human-tumbled and polished.

Identified September 13, 2026More mineral →

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Physical properties

Mohs hardness 7; translucent purple with vitreous luster, conchoidal fracture, and no cleavage. Crystalline quartz structure; the smooth rounded shape is human-tumbled and polished.

Formation & geological history

Forms in cavities of volcanic rocks, especially basaltic geodes, when silica-rich hydrothermal fluids deposit quartz; purple color develops through iron-related defects and natural irradiation. Most specimens formed in relatively young volcanic environments, commonly within the last few hundred million years.

Uses & applications

Used as an ornamental stone, in jewelry, carvings, lapidary objects, and mineral collections. Tumbled pieces are inexpensive decorative specimens.

Geological facts

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

Field identification & locations

Identify by purple color, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; beware dyed glass or quartz. Major sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico.