metamorphic

Quartzite

Quartzite (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: hexagonal (as constituent grains); Cleavage: none; Specific gravity: 2.6-2.7

Hardness: 7 on Mohs scale
Color: white to light gray
Luster: vitreous to dull

Identified July 16, 2026More metamorphic →

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Physical properties

Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: hexagonal (as constituent grains); Cleavage: none; Specific gravity: 2.6-2.7

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together into a dense, hard rock.

Uses & applications

Used in construction as road ballast, for building stone, roofing tiles, and as a source of silica for glass making and industrial abrasives.

Geological facts

Quartzite is so hard that it will scratch steel. It is one of the most resistant rocks to chemical and physical weathering, often forming the peaks of mountain ranges.

Field identification & locations

Identify by its ability to scratch glass and its granular, sugary appearance. Unlike marble, it will not fizz when exposed to dilute acid. Common in metamorphic mountain belts worldwide.