gemstone

Amethyst

Purple quartz; silicon dioxide (SiO₂), colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Hardness 7 Mohs; violet to purple, translucent, with a vitreous luster and hexagonal crystal structure. Quartz has no true cleavage and commonly shows conchoidal fracture; the specimen appears rough and possibly partially polished.

Identified September 13, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in cavities of volcanic rocks, especially basaltic lava flows, when silica-rich hydrothermal fluids crystallize over geologic time, commonly from the Cenozoic to older volcanic episodes.

Uses & applications

Used as a gemstone, ornamental stone, mineral specimen, and in metaphysical collections; quality depends on color saturation, transparency, crystal form, and size.

Geological facts

Amethyst is the purple variety of quartz and is the February birthstone. Heating can turn it yellow-orange, producing citrine or ametrine in suitable material.

Field identification & locations

Identify it by its purple color, glassy luster, quartz-like hardness, and lack of cleavage; glass and fluorite are common look-alikes. Major sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico.