metamorphic
Quartzite Pebble
Quartzite (principally Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal Structure: Trigonal (microcrystalline); Cleavage: none; Specific Gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- white to light gray
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal Structure: Trigonal (microcrystalline); Cleavage: none; Specific Gravity: 2.63-2.65
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, followed by river or ocean erosion that rounded it into a pebble shape over thousands of years.
Uses & applications
Used in construction as road ballast, in glass manufacturing if high purity, and as decorative lawn or garden stones.
Geological facts
Quartzite is harder than the sandstone it originated from and is so tough that it often breaks through the quartz grains rather than around them.
Field identification & locations
Identified by its extreme hardness (cannot be scratched by a steel knife) and its grainy, sugary texture. Commonly found on beaches and in riverbeds.
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