metamorphic

Quartzite

Quartzite (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: white to pale pinkish-tan; Luster: vitreous to dull; Crystal Structure: non-foliated, interlocking quartz grains; Cleavage: none (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 7 on Mohs scale
Color: white to pale pinkish-tan
Luster: vitreous to dull

Identified April 8, 2026More metamorphic →

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Physical properties

Formation & geological history

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

Uses & applications

Used as crushed stone for road construction, railroad ballast, and as a raw material in the glass and ceramics industries. Finer specimens are used for decorative landscaping and interior design.

Geological facts

Quartzite is so tough that it often outlasts the surrounding rocks during erosion, often forming the peaks of hills and mountain ranges. It is harder than steel and will easily scratch a glass plate.

Field identification & locations

Identify in the field by its extreme hardness, grainy 'sugary' texture, and the way it breaks across the grains rather than around them (unlike sandstone). Commonly found in mountain belts and riverbeds.