gemstone

Amethyst crystal point

Quartz, purple variety — silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; typically transparent to translucent purple, with vitreous luster and hexagonal crystal structure. Quartz lacks cleavage and has conchoidal fracture; purple color comes mainly from iron impurities and irradiation.

Identified August 16, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in cavities of volcanic rocks, especially basalt, when silica-rich hydrothermal fluids deposit quartz and trace iron over geologic time, commonly during Mesozoic to Cenozoic volcanism. The image appears to show a polished or artificially shaped point rather than a natural crystal termination.

Uses & applications

Used for jewelry, ornamental carvings, crystal points, and mineral collecting; lower-grade material is sold as decorative stone. Fine deep-purple, well-formed specimens have the greatest value.

Geological facts

Amethyst is the birthstone for February and is the most valuable common quartz variety. Heating can turn it yellow-orange, producing citrine.

Field identification & locations

Identify by its purple quartz appearance, glassy luster, hardness, and lack of cleavage; it commonly occurs in Brazil, Uruguay, Zambia, and Mexico. Value is roughly $10–$75 for a common polished point, or $100–$1,000+ for large, vivid, naturally terminated specimens.