mineral

Amethyst quartz crystal

Quartz, SiO₂, purple variety (amethyst)

AI-generated identification · may be incorrect

Hardness 7 Mohs; purple to violet color with vitreous luster, commonly showing hexagonal crystal structure and conchoidal fracture rather than cleavage. The specimen appears to be a small rough crystal cluster or matrix piece.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms when iron-bearing quartz is irradiated in volcanic cavities, hydrothermal veins, or geodes; many deposits formed during the Cenozoic and older volcanic episodes. Common sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico.

Uses & applications

Used for jewelry, ornamental objects, lapidary pieces, and mineral collecting; commercial value depends strongly on color, transparency, crystal form, and locality.

Geological facts

The purple color results mainly from irradiation-related defects involving iron impurities. Heating can turn some amethyst yellow or orange, producing citrine-like material.

Field identification & locations

Identify by its purple color, glassy luster, hardness, and lack of obvious cleavage; it should scratch glass but not be scratched by a steel knife. Common field associations include white quartz, calcite, basalt, and agate.