mineral

Amethyst cluster

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; purple, vitreous luster, transparent to translucent, with hexagonal quartz crystals and indistinct cleavage. Purple color results mainly from iron impurities and irradiation.

Identified September 16, 2026More mineral →

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Physical properties

Mohs hardness 7; purple, vitreous luster, transparent to translucent, with hexagonal quartz crystals and indistinct cleavage. Purple color results mainly from iron impurities and irradiation.

Formation & geological history

Forms when silica-rich hydrothermal fluids or groundwater deposit quartz in cavities of volcanic rocks, especially basalt and rhyolite; commonly Cenozoic to older. This specimen appears to be a natural crystal cluster, possibly from a geode cavity.

Uses & applications

Used for jewelry, ornamental objects, crystal collecting, and lapidary work; fine, deeply saturated crystals have the greatest value.

Geological facts

Amethyst is the February birthstone and a variety of quartz; heating can turn it yellow or orange, producing citrine-like material.

Field identification & locations

Identify by its purple color, glassy luster, hardness, and six-sided crystal faces; it should scratch glass but not be scratched by a steel blade. Major sources include Brazil, Uruguay, Zambia, and Mexico.