metamorphic
Quartzite Pebbler
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: tan, white, or light brownish; Luster: dull to vitreous; Crystal Structure: Trigonal (granular texture); Cleavage: none (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- tan, white, or light brownish
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: tan, white, or light brownish; Luster: dull to vitreous; Crystal Structure: Trigonal (granular texture); Cleavage: none (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone. High heat and pressure causes recrystallization of the sand grains. This specific specimen has been rounded and smoothed by water erosion through transport in a river or stream.
Uses & applications
Commonly used in construction as crushed stone, railway ballast, and occasionally for lapidary work or landscape stones.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caprock on mountains. It is harder than the steel of a pocket knife, which will leave a metallic streak on the stone rather than scratching it.
Field identification & locations
Identify by its hardness (scratches glass) and granular texture that looks like fused sand grains. Commonly found in riverbeds, glacial deposits, and mountainous regions.
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