mineral

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Transparent/colorless. Luster: Vitreous (glass-like). Crystal Structure: Trigonal/Hexagonal. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Transparent/colorless
Luster: Vitreous (glass-like)

Identified July 23, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale. Color: Transparent/colorless. Luster: Vitreous (glass-like). Crystal Structure: Trigonal/Hexagonal. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Formed in late stages of igneous crystallization within pegmatites, as well as in hydrothermal veins, metamorphic rocks, and sedimentary deposits under a wide range of temperatures and pressures.

Uses & applications

Used widely in gemstone jewelry, ornamental carvings, electronics (piezoelectric oscillators in watches and radios), glass making, and specimen collections.

Geological facts

Ancient Greeks believed clear quartz was ice frozen so deeply that it would never melt, calling it 'krystallos' (meaning ice), from which the word 'crystal' derives.

Field identification & locations

Identified in the field by its hexagonal crystal habit, glass-like transparency, ability to scratch glass (Mohs 7), and lack of cleavage. Common worldwide, with famous deposits in Brazil, Madagascar, Arkansas (USA), and the Alps.