metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: greyish-white with iron oxidation stains; Luster: vitreous to waxy; Crystal structure: hexagonal (microcrystalline); Cleavage: none; Specific gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- greyish-white with iron oxidation stains
- Luster
- vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: greyish-white with iron oxidation stains; Luster: vitreous to waxy; Crystal structure: hexagonal (microcrystalline); Cleavage: none; Specific gravity: 2.63-2.65
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. Under intense heat and pressure, the individual quartz grains recrystallize into a locked mosaic of crystals. Most specimens date from the Proterozoic or Paleozoic eras.
Uses & applications
Used primarily as construction aggregate, ballast, and in some architectural landscaping. High-purity quartzite is used to produce glass and industrial silica.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, resulting in high mountain ridges or smooth river pebbles like this one. It will scratch glass easily.
Field identification & locations
Identify by its extreme hardness and sugary, crystalline appearance when broken. This specific specimen is smooth due to water erosion (fluvial or beach action). Commonly found in ancient mountain belts and river beds.
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