metamorphic
Quartzite
SiO2 (Silicon Dioxide / Metamorphic Quartz)
Hardness: 7 on the Mohs scale. Color: Pale pinkish-purple to grayish-brown with sub-vitreous to greasy luster. Conchoidal fracture and interlocking granular texture.
- Hardness
- 7 on the Mohs scale
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Physical properties
Hardness: 7 on the Mohs scale. Color: Pale pinkish-purple to grayish-brown with sub-vitreous to greasy luster. Conchoidal fracture and interlocking granular texture.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone under high heat and pressure, causing quartz grains to recrystallize and interlock tightly.
Uses & applications
Used as crushed stone in road construction, railway ballast, dimension stone, and as raw material for silica manufacturing. Polished pebbles are collected and used in decorative landscapes.
Geological facts
Unlike sandstone which breaks around its quartz grains, quartzite breaks directly through the constituent quartz crystals due to its dense, recrystallized structure.
Field identification & locations
Look for a very hard pebble that scratches glass easily and exhibits a sugary to glassy fracture surface. Commonly found along riverbeds, beaches, and glaciated terrain.
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