metamorphic
Red Quartzite River Rock
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Reddish-brown due to iron oxide impurities; Luster: Dull to vitreous when wet; Structure: Granular, non-foliated; Cleavage: None, breaks with conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown due to iron oxide impurities
- Luster
- Dull to vitreous when wet
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-brown due to iron oxide impurities; Luster: Dull to vitreous when wet; Structure: Granular, non-foliated; Cleavage: None, breaks with conchoidal fracture.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. The specimen shown is a well-rounded river cobble, suggesting long-term transport and erosion in a fluvial environment.
Uses & applications
Commonly used in landscaping, as decorative garden stones, and sometimes as a hard aggregate in specialized high-strength concrete or road construction.
Geological facts
Quartzite is so hard and chemically resistant that it often survives through multiple cycles of erosion, outlasting the original mountains in which it formed.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife) and its grainy, sugary texture visible on broken surfaces. Found in riverbeds and glacial deposits globally.
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