mineral

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Colorless to transparent; Luster: Vitreous (glass-like); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Colorless to transparent
Luster: Vitreous (glass-like)

Identified May 16, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Colorless to transparent; Luster: Vitreous (glass-like); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Forms in igneous, metamorphic, and sedimentary environments through the cooling of silica-rich magma or precipitation from hydrothermal fluids. Found in abundance throughout Earth's crust across all geological ages.

Uses & applications

Used in electronics for its piezoelectric properties, glassmaking, construction (as sandpaper or abrasives), jewelry, and as a popular decorative or collecting specimen.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is known as rock crystal; it was once believed by ancient Greeks to be ice that had frozen so hard it would never melt.

Field identification & locations

Identify by its hardness (scratches glass), lack of cleavage, and hexagonal crystal habit (though this specimen is polished). Found globally, notably in Brazil, USA (Arkansas), and Madagascar.