Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: typically white to gray, often pink or reddish due to iron oxides; Luster: vitreous to dull; Crystal structure: hexagonal (as quartz grains); Cleavage: none, breaks with a conchoidal or irregular fracture; Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone subjected to high heat and pressure, causing the original quartz grains to recrystallize and fuse together into a dense, hard mass.

Uses & Applications

Used extensively in construction as crushed stone for road beds and railway ballast, as a decorative stone in countertops and wall cladding, and as a source of silica for glass manufacturing.

Geological Facts

Quartzite is so hard and chemically resistant that it often forms prominent ridges and hills in mountain ranges. It is harder than a steel knife and will scratch glass easily.

Field Identification & Locations

Identify in the field by its sugary texture on fresh surfaces and its inability to be scratched by a steel blade. It commonly occurs in metamorphic belts and can be found in mountain ranges globally.

Identified on: 5/4/2026

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