metamorphic
Quartzite River Rock
Metamorphic Rock (Recrystallized Quartz - SiO2)
Hardness: 7 (Mohs scale); Color: Grayish-tan with white veins and rusty staining; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Specific Gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Grayish-tan with white veins and rusty staining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-tan with white veins and rusty staining; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under extreme heat and pressure, often during mountain-building events. This specimen has been smoothed and rounded by long-term fluvial (river) erosion.
Uses & applications
Commonly used in landscaping, as a building stone, crushed for road base, or used in the manufacturing of glass and ceramics due to high silica content.
Geological facts
Quartzite is so tough that it often survives intense erosion cycles that destroy other rocks, which is why it is often found as rounded cobbles in riverbeds far from its original source.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by steel) and its sugary, granular appearance on fresh surfaces. It is found globally in mountainous and erosional environments.
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