Amethyst

Physical Properties

Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous/glassy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Formation & Geological History

Formed in hydrothermal veins or geodes when silica-rich water fills cavities in volcanic rocks (like basalt or rhyolite). The purple color is caused by trace amounts of iron irradiated by gamma rays. Found in deposits ranging from millions of years old to relatively younger formations.

Uses & Applications

Primarily used for decorative purposes, jewelry (faceted gems and cabochons), crystal healing collections, and industrial uses if high-purity silica is required.

Geological Facts

Amethyst was once considered one of the five cardinal gems (alongside diamond, ruby, emerald, and sapphire) until large deposits were found in Brazil in the 1700s, making it more affordable.

Field Identification & Locations

Identify by its distinctive purple hue and hexagonal crystal shape if unpolished. To verify in the field, look for quartz-like glassiness and test for a hardness of 7 (should scratch glass but not be scratched by a steel file). Commonly found in Brazil, Uruguay, Zambia, and Ontario.

Identified on: 4/26/2026

Mode: Standard