metamorphic
Quartzite (River Pebble)
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, yellowish-brown, and white; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 - 2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, yellowish-brown, and white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, yellowish-brown, and white; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 - 2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, causing the individual quartz grains to recrystallize into a locked interlocking mosaic. This specimen shows significant rounding from alluvial/river transport.
Uses & applications
Used primarily as decorative river rock in landscaping, as an abrasive, and in construction as road ballast or concrete aggregate.
Geological facts
Quartzite is so durable that it can survive billions of years of erosion. It is often harder than the steel of a knife. The yellowish staining on the exterior of this piece is likely due to iron oxide (limonite) penetration from the environment.
Field identification & locations
Identify in the field by its inability to be scratched by a steel blade and its granular, sugary texture on fresh breaks. It is ubiquitous in riverbeds and glacial deposits globally.
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