metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous/waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Milky white to tan
- Luster
- Vitreous/waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous/waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing recrystallization of quartz grains. Commonly found in riverbeds or beaches where water erosion has rounded the specimen.
Uses & applications
Used as decorative stone in landscaping, a high-quality abrasive in industrial processes, and occasionally as a low-cost gemstone or aggregate in construction.
Geological facts
Quartzite is so hard that it will scratch glass and steel. Most quartzite is over 90% quartz, making it one of the most chemically stable rocks on Earth.
Field identification & locations
Identify in the field by its extreme hardness and grainy yet fused texture. It is often found in glacial deposits or active river systems as smooth 'river rocks'.
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