mineral

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Hardness: 7 Mohs. Color: Colorless. Luster: Vitreous. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific gravity: 2.65.

Hardness: 7 Mohs
Color: Colorless
Luster: Vitreous

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 7 Mohs. Color: Colorless. Luster: Vitreous. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific gravity: 2.65.

Formation & geological history

Forms in a wide variety of environments, most commonly by crystallization from molten magma or hydrothermal veins. It is found in igneous, metamorphic, and sedimentary rocks across all geological ages.

Uses & applications

Used in jewelry, decorative carvings, watch movements (piezoelectric properties), and glassmaking. Highly valued by crystal collectors for its clarity.

Geological facts

Clear quartz is also known as 'Rock Crystal'. The word quartz comes from the Greek word 'krustallos', meaning ice, as the ancients believed it was ice frozen so hard it would never melt.

Field identification & locations

Identify by its hardness (scratches glass), lack of cleavage, and hexagonal crystal habit. Found worldwide, with major deposits in Brazil, Madagascar, and the USA (Arkansas).