metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan with iron staining; Luster: dull to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: none, breaks with conchoidal fracture; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or tan with iron staining
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan with iron staining; Luster: dull to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: none, breaks with conchoidal fracture; Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, usually during mountain-building events. This specific specimen has been further shaped and rounded by fluvial or glacial erosion.
Uses & applications
Used primarily in construction as crushed stone or ballast. High-purity quartzite is used to produce silica sand for glassmaking and silicon for electronics. Smooth pebbles are popular for landscaping.
Geological facts
Quartzite is so durable that it often survives multiple cycles of erosion and deposition. It is often harder and more resistant than the parent sandstone it originated from.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary texture under a hand lens. Commonly found in riverbeds, glacial tills, and ancient mountain belts. It is extremely weather-resistant.
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