mineral

Amethyst cluster

Quartz, purple variety — SiO₂, colored mainly by irradiation and iron-related impurities

AI-generated identification · may be incorrect

Violet, transparent-to-translucent quartz crystals with vitreous luster and hexagonal crystal forms; hardness 7 Mohs, no cleavage, conchoidal fracture, specific gravity about 2.65. The white base is likely quartz or a quartz-rich host matrix.

Identified September 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basalt, where quartz crystals grow inward over long periods. The photographed specimen is likely relatively young geologically, commonly Cenozoic, though its exact age cannot be determined visually.

Uses & applications

Used as a decorative and collecting specimen, in jewelry, carvings, and occasionally as an ornamental stone. Common-quality clusters generally have modest commercial value.

Geological facts

Amethyst’s purple color can fade with prolonged heating or strong sunlight; heating may produce yellow citrine-like material. Darker, well-formed crystals are typically more desirable.

Field identification & locations

Identify by purple quartz crystals, glassy luster, hardness near 7, and lack of cleavage. Major sources include Brazil, Uruguay, Zambia, and Bolivia; southern coastal California can contain quartz veins and cavities, but this specimen’s exact origin cannot be confirmed from the stated location.