metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: light grey to white; Luster: vitreous to dull; Crystal structure: granular/crystalline; Cleavage: none; Specific gravity: approx. 2.65.
- Hardness
- 7 on Mohs scale
- Color
- light grey to white
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: light grey to white; Luster: vitreous to dull; Crystal structure: granular/crystalline; Cleavage: none; Specific gravity: approx. 2.65.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. These pebbles are often rounded by water erosion in rivers or coastal environments.
Uses & applications
Crushed quartzite is used in construction as road ballast and in the manufacturing of glass and ceramics. Polished pebbles are used in landscaping and aquariums.
Geological facts
Quartzite is so durable that it often survives intense weathering and transport to form high-purity sand and pebbles. It is one of the hardest common rocks found on Earth's surface.
Field identification & locations
Identify in the field by its hardness (it can scratch glass) and its granular appearance. Unlike sandstone, quartzite breaks across the sand grains rather than around them. Common in riverbeds and glacial deposits.
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