metamorphic
Quartzite
Quartzite (chiefly SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, often with reddish or yellowish tints; Luster: vitreous to dull; Structure: non-foliated, granular; Cleavage: none; SG: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray, often with reddish or yellowish tints; Luster: vitreous to dull; Structure: non-foliated, granular; Cleavage: none; SG: 2.6-2.7.
Formation & geological history
Formed from the regional metamorphism of quartz sandstone under high heat and pressure, causing quartz grains to recrystallize into a dense network of interlocking crystals.
Uses & applications
Used as a decorative stone in construction, crushed stone for road ballast, and in the manufacturing of glass and ceramics due to high silica content.
Geological facts
Quartzite is so hard and durable that it often forms the crests of ridges and hills. It can withstand chemical weathering much better than the rocks around it.
Field identification & locations
Identify in the field by its sugary texture and extreme hardness (it will easily scratch glass). It breaks through grains rather than around them, unlike sandstone. Common in fold mountain belts.
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