metamorphic
Quartzite Pebble
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Off-white to light tan; Luster: Dull to waxy; Texture: Granular, crystalline; Cleavage: None; SG: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Off-white to light tan
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white to light tan; Luster: Dull to waxy; Texture: Granular, crystalline; Cleavage: None; SG: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen shows significant rounding and smoothing due to fluvial (river) or coastal erosion processes.
Uses & applications
Used in construction as crushed stone or ballast, in glass manufacturing if pure enough, and as decorative river stones in landscaping.
Geological facts
Quartzite is so hard and chemically resistant that it often survives long after the surrounding rock has eroded away. It is tougher than the sandstone it originates from because the quartz grains are fused together.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its lack of reaction to acid. Often found in riverbeds, glacial deposits, and mountain ranges. This specific piece is a water-worn cobble.
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