metamorphic
Quartzite (Orthoquartzite)
SiO2 (Silicon Dioxide) with Iron Oxide inclusions
Hardness: 7 on Mohs scale; Color: Pinkish-orange or salmon due to hematite impurities; Luster: Vitreous to waxy; Structure: Crystalline, non-foliated; Cleavage: None, fractures conchoidally.
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-orange or salmon due to hematite impurities
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Pinkish-orange or salmon due to hematite impurities; Luster: Vitreous to waxy; Structure: Crystalline, non-foliated; Cleavage: None, fractures conchoidally.
Formation & geological history
Originally formed as quartz-rich sandstone in beach or desert environments. Over geological time (Precambrian to Paleozoic), intense heat and pressure from tectonic activity fused the sand grains into a solid rock mass.
Uses & applications
Commonly used as crushed stone in construction, as decorative landscaping stone, and occasionally in glassmaking or as a semi-precious stone for lapidary work.
Geological facts
Quartzite is so tough that it often outlasts other rocks during erosion, forming the peaks of many mountain ranges. It is harder and more durable than the sandstone from which it originated.
Field identification & locations
Identify in the field by its hardness (will scratch glass easily) and its sugary texture that sparkles under light. Found globally in ancient mountain belts and glacial deposits.
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