metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: white, grey, or tan with crystalline texture; Luster: vitreous to dull; Crystal structure: hexagonal (within grains); specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- white, grey, or tan with crystalline texture
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: white, grey, or tan with crystalline texture; Luster: vitreous to dull; Crystal structure: hexagonal (within grains); specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing the individual quartz grains to recrystallize into a hard, interlocking network.
Uses & applications
Commonly used as construction aggregate, railway ballast, and in some industrial manufacturing of glass or ceramics. Smooth pebbles are often used in landscaping.
Geological facts
Quartzite is so hard that it will scratch glass and steel. In the field, it can be distinguished from sandstone because it breaks across the quartz grains rather than around them.
Field identification & locations
Look for a sugary, crystalline texture on broken surfaces. It is found in mountainous regions or ancient coastal deposits all over the world, often appearing as highly weather-resistant rounded river stones.
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