metamorphic
Red Quartzite
Metamorphic Quartzite (predominantly SiO2 with iron oxide impurities)
Hardness: 7 on Mohs scale; Color: Reddish-pink to brownish-red; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Reddish-pink to brownish-red
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-pink to brownish-red; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen shows signs of fluvial erosion (river rounding). Often Proterozoic to Paleozoic in age.
Uses & applications
Used in construction as road ballast, railway ballast, and decorative stone. Sometimes used in jewelry or as 'pocket stones' when polished.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of ridges and mountains. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify by its extreme hardness and sugary, crystalline texture on a fresh break. Commonly found in glacial till and riverbeds across North America, especially the Great Lakes region.
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