mineral

Tumbled amethyst-bearing quartz

Quartz, SiO₂; purple coloration from iron-related defects and irradiation

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent white to lavender-purple with yellow-brown iron-oxide staining or inclusions; vitreous luster, hexagonal crystal structure, no cleavage, conchoidal fracture. The rounded shape indicates tumbling or polishing.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, commonly alongside iron minerals; many deposits formed in Mesozoic to Cenozoic volcanic environments. The specimen may be a mixed amethyst/quartz piece rather than a single crystal.

Uses & applications

Used for inexpensive jewelry, ornaments, crystal collections, and lapidary work; amethyst-quality material is cut as a gemstone, while heavily included pieces are mainly decorative.

Geological facts

Purple quartz is called amethyst; yellow-brown areas are likely limonite/goethite or citrine-like iron staining. Strong heat can fade or alter the purple color.

Field identification & locations

Identify by its glassy luster, hardness, translucent quartz body, and purple coloration; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, and the United States.