metamorphic

Quartzite

Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs, Color: tan to creamy white, Luster: vitreous to waxy (especially when polished), Crystal Structure: trigonal (microcrystalline), Cleavage: none, Specific Gravity: 2.6-2.7

Identified July 9, 2026More metamorphic →

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Physical properties

Hardness: 7 Mohs, Color: tan to creamy white, Luster: vitreous to waxy (especially when polished), Crystal Structure: trigonal (microcrystalline), Cleavage: none, Specific Gravity: 2.6-2.7

Formation & geological history

Formed from the metamorphism of quartz sandstone under high heat and pressure, causing quartz grains to recrystallize and fuse together. Typically Precambrian to Paleozoic age depending on location.

Uses & applications

Used as a decorative stone, in construction as crushed stone for road gravel and railway ballast, and in the ceramic and glass industries. Polished specimens are popular for meditation and home decor.

Geological facts

Quartzite is so strong that when it breaks, it fractures through the quartz grains rather than along the boundaries between them, unlike sandstone.

Field identification & locations

Identified by its extreme hardness (cannot be scratched by a steel knife) and its grainy but fused texture. Often found in mountain ranges where tectonic plates have collided.