metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale. Color: White to light grey. Luster: Vitreous to dull. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.6–2.7.
- Hardness
- 7 on Mohs scale
- Color
- White to light grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale. Color: White to light grey. Luster: Vitreous to dull. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.6–2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events (orogeny). This specimen has been smoothed and rounded by water erosion in a river or beach environment.
Uses & applications
Used as a decorative stone in landscaping, for railroad ballast, and as a source of silica in glass manufacturing or construction aggregate.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the ridges and peaks of mountain ranges because it resists weathering better than surrounding rocks.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its grainy, sugary appearance despite being a solid mass. Commonly found in riverbeds, glacial deposits, and coastal areas.
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