gemstone

Amethyst (rough quartz)

Quartz, SiO₂; purple variety colored mainly by iron-related defects and irradiation

AI-generated identification · may be incorrect

Hardness 7 Mohs; pale to medium purple, translucent, and vitreous to dull on the rough surface. Hexagonal crystal structure; cleavage is absent, with conchoidal fracture; typical specific gravity is about 2.65.

Identified September 16, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, commonly alongside iron minerals. Most deposits formed in geologically young to mid-age volcanic provinces, often during the Mesozoic or Cenozoic.

Uses & applications

Used for beads, cabochons, faceted gemstones, carvings, specimens, and ornamental objects; large geodes are decorative. This piece appears rough and modestly collectible.

Geological facts

Purple color can fade with prolonged heating or strong sunlight. Amethyst is the February birthstone and is often found lining basalt vesicles.

Field identification & locations

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