Amethyst (Rough Quartz)

Physical Properties

Hardness: 7 on Mohs scale; Color: Pale lavender to deep violet; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65

Formation & Geological History

Formed in hydrothermal veins or cavities (geodes) when silica-rich water precipitates quartz. The purple color comes from irradiation of iron impurities over millions of years.

Uses & Applications

Widely used in jewelry (faceting and cabochons), crystal healing practices, as interior decor, and for mineral collection specimens.

Geological Facts

Amethyst was once considered one of the five cardinal gemstones alongside diamonds and rubies until large deposits were found in Brazil in the 1700s, making it more common.

Field Identification & Locations

Identify by its purple hue, lack of cleavage, and ability to scratch glass. Found commonly in Brazil, Uruguay, Zambia, and Ontario, Canada (notably the Thunder Bay area).

Identified on: 5/15/2026

Mode: Standard