Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: tan to yellowish/white, Luster: vitreous to waxy, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together. Often found in Precambrian or Paleozoic metamorphic belts.

Uses & Applications

Used as a decorative stone, in construction as crushed stone or flooring, and in manufacturing high-purity silica products.

Geological Facts

Quartzite is so hard that it will scratch glass and steel. It is more resistant to weathering than the sandstone it originated from, often forming prominent ridges and hills.

Field Identification & Locations

Identify in the field by its hardness and its tendency to break across grain boundaries rather than around them (unlike sandstone). Commonly found in ancient mountain ranges and river gravels.

Identified on: 5/5/2026

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