gemstone

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple color with vitreous luster, typically lacking visible cleavage and showing conchoidal fracture. The specimen is polished/tumbled, with color likely from trace iron and irradiation.

Identified August 18, 2026More gemstone →

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Physical properties

Formation & geological history

Forms mainly in silica-rich volcanic cavities as quartz crystals, often during hydrothermal activity; deposits range from Paleozoic to Cenozoic in age. Common sources include Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used in jewelry, carvings, ornamental objects, and mineral collecting; tumbled stones are inexpensive decorative and lapidary material.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone. Heating can turn it yellow-orange, producing citrine or ametrine-like colors.

Field identification & locations

Identify by purple quartz color, glassy luster, hardness, and lack of cleavage; glass may imitate it but is generally softer and may show bubbles. Common field/locality associations include basaltic geodes and hydrothermal veins.