metamorphic
Quartzite Cobble
Metamorphosed Quartz Sandstone (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Tan to light brown with iron oxide staining; Luster: Dull to vitreous; Structure: Crystalline, granular texture; Cleavage: None
- Hardness
- 7 on Mohs scale
- Color
- Tan to light brown with iron oxide staining
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan to light brown with iron oxide staining; Luster: Dull to vitreous; Structure: Crystalline, granular texture; Cleavage: None
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. This specimen has been rounded into a cobble by water erosion in a river or glacial environment.
Uses & applications
Used as construction aggregate, river rock for landscaping, and historically for making stone tools due to its hardness and conchoidal fracture.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of ridges and mountains. It is tougher than the parent sandstone from which it originated.
Field identification & locations
Identify in the field by its ability to scratch glass and its grainy, sugary appearance despite its hardness. Often found in riverbeds or glacial tills.
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