mineral

Amethyst-bearing quartz cluster

Quartz, SiO₂; purple coloration from irradiation and trace iron

AI-generated identification · may be incorrect

Typically Mohs hardness 7, glassy luster, translucent to transparent, hexagonal crystal system, and indistinct cleavage with conchoidal fracture. This specimen shows pale purple amethyst crystals with colorless-to-greenish quartz and a rough gray matrix.

Identified August 20, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystals formed in open cavities of volcanic rocks, commonly basaltic geodes, as silica-rich hydrothermal fluids cooled; many deposits are Cenozoic, though quartz formation spans geologic time. The purple color developed through iron impurities and natural radiation.

Uses & applications

Used as a decorative mineral, lapidary material, jewelry gemstone, and collector specimen; quartz is also important industrially in glass, electronics, and abrasives. Value depends strongly on color, crystal size, damage, and locality.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone. Heating can turn some amethyst yellow or orange, producing citrine-like material.

Field identification & locations

Identify by its purple quartz crystals, hardness, vitreous luster, and lack of cubic cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, and Mexico.