metamorphic
Quartzite river pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with tan weathering; Luster: Dull/earthy (unpolished surface); Crystal structure: Granular, interlocking quartz grains; Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with tan weathering
- Luster
- Dull/earthy (unpolished surface)
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with tan weathering; Luster: Dull/earthy (unpolished surface); Crystal structure: Granular, interlocking quartz grains; Specific gravity: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific piece has been rounded into a pebble (cobble) by water erosion in a river or coastal environment over thousands of years.
Uses & applications
Used in construction as crushed stone, road ballast, or landscaping. High-purity quartzite is used in glass making and metallurgy.
Geological facts
Quartzite is one of the most durable rocks on Earth's surface. It is so hard that it will scratch glass and steel, and it often survives millions of years of erosion where other rocks have crumbled.
Field identification & locations
Identified in the field by its hardness and granular, sugary appearance on a fresh break. Found globally in ancient mountain belts and as river-rolled gravels.
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