mineral

Amethyst (Rough)

Quartz, SiO2

Hardness: 7 (Mohs scale), Color: Light to dark purple, Luster: Vitreous, Crystal structure: Trigonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Identified June 17, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Light to dark purple, Luster: Vitreous, Crystal structure: Trigonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Formation & geological history

Forms in vugs/geodes in igneous rocks (often basalt) from silica-rich hydrothermal fluids. The purple color comes from irradiation, iron impurities, and the presence of trace elements.

Uses & applications

A highly valued semi-precious gemstone used extensively in jewelry, lapidary arts, and for collection or decorative purposes.

Geological facts

Amethyst is the birthstone for February. Historically, it was believed to prevent intoxication.

Field identification & locations

Identify by its characteristic purple color, hardness of 7 (will scratch glass), and conchoidal fracture. Common locations include Brazil, Uruguay, Zambia, and parts of the US. Rough pieces like this are often found by breaking open geodes.