metamorphic
River Quartzite (River Pebble)
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, brown, or buff; Luster: Dull to vitreous; Crystal Structure: Hexagonal (microcrystalline); Growth: Dense, interlocking grains; Specific Gravity: approx 2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, or buff
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, or buff; Luster: Dull to vitreous; Crystal Structure: Hexagonal (microcrystalline); Growth: Dense, interlocking grains; Specific Gravity: approx 2.65
Formation & geological history
Formed from the recrystallization of quartz-rich sandstone under intense heat and pressure (metamorphism). This specific specimen has been further shaped and polished by fluvial (river) erosion over thousands of years.
Uses & applications
Primarily used in landscaping, architectural facing, and as decorative river stone. Industrially, crushed quartzite is used in road construction and as a source of silica.
Geological facts
Quartzite is so tough that it often survives the weathering process much longer than the surrounding rocks, which is why it is frequently found as rounded cobbles in river beds far from its source ledge.
Field identification & locations
Identify by its hardness (it will easily scratch glass) and its dense, granular texture that looks like boiled sugar. Common in riverbeds, glacial tills, and mountainous regions worldwide.
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