mineral

Tumbled dark purple quartz, likely amethyst

Quartz (SiO₂), purple variety amethyst; possibly iron-bearing quartz with surface sparkle

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent to opaque gray-purple color, vitreous luster, hexagonal crystal structure, and no cleavage (conchoidal fracture). The rounded edges indicate tumbling or natural abrasion.

Identified August 13, 2026More mineral →

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Physical properties

Hardness 7 Mohs; translucent to opaque gray-purple color, vitreous luster, hexagonal crystal structure, and no cleavage (conchoidal fracture). The rounded edges indicate tumbling or natural abrasion.

Formation & geological history

Amethyst forms when iron-bearing quartz crystallizes in cavities of volcanic rocks, commonly basalt, and later develops purple color through irradiation and trace iron. Most specimens formed in Phanerozoic volcanic environments, especially in Brazil, Uruguay, and Africa.

Uses & applications

Used for inexpensive jewelry, ornaments, crystal collections, and lapidary work; larger crystalline specimens have decorative value.

Geological facts

Purple color can fade with strong heat or sunlight. Sparkly surfaces may reflect tiny quartz crystal faces or mica-like inclusions rather than indicating metallic ore.

Field identification & locations

Identify by its purple hue, glassy luster, hardness, and inability to scratch it with a steel blade; quartz should scratch ordinary glass. Common sources include Brazil, Uruguay, Zambia, and Morocco.