metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan; Luster: vitreous to dull; Crystal structure: trigonal (granular); Cleavage: none; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or tan
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan; Luster: vitreous to dull; Crystal structure: trigonal (granular); Cleavage: none; Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure. This specimen shows significant rounding, suggesting it was once a river cobble or pebble.
Uses & applications
Used as decorative stone in landscaping, crushed stone for road construction, and sometimes in high-end glass manufacturing or as floor tiling.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges it was part of, frequently being found as rounded pebbles in younger sedimentary basins.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its granular texture that looks like sand grains fused together. Found in mountainous or glaciated regions worldwide.
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