metamorphic
Quartzite Pebble
Quartzite (primarily Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: yellowish-tan to grey; Luster: vitreous to dull; Crystal structure: hexagonal/trigonal (microcrystalline); Cleavage: none; Specific gravity: ~2.65
- Hardness
- 7 on Mohs scale
- Color
- yellowish-tan to grey
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: yellowish-tan to grey; Luster: vitreous to dull; Crystal structure: hexagonal/trigonal (microcrystalline); Cleavage: none; Specific gravity: ~2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing the original quartz grains to recrystallize into an interlocking mosaic.
Uses & applications
Used primarily as construction aggregate, railway ballast, and occasionally as decorative stones or in landscaping.
Geological facts
Quartzite is so tough that it usually breaks through the quartz grains rather than along their boundaries, unlike sandstone which breaks between the grains.
Field identification & locations
Identify in the field by its hardness (will scratch glass) and lack of reaction to acid. Commonly found in riverbeds or glacial deposits as rounded cobbles.
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