metamorphic
Quartzite River Rock
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with iron staining (yellow/brown); Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Specific gravity: 2.6 - 2.65
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with iron staining (yellow/brown)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with iron staining (yellow/brown); Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Specific gravity: 2.6 - 2.65
Formation & geological history
Formed through the metamorphism of quartz sandstone under intense heat and pressure. This specific specimen shows rounding from alluvial transport in a river or glacial environment.
Uses & applications
Commonly used as decorative landscaping stone, in construction as crushed stone or ballast, and as a source of silica in glass manufacturing.
Geological facts
Quartzite is so tough that it often survives the weathering process better than the surrounding rocks, which is why it is frequently found as rounded cobbles in stream beds millions of years after formation.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its grainy, sugary texture under a hand lens. This specimen shows typical 'chatter marks' or impact scars from tumbling in water.
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