metamorphic
River Pebble (Quartzite)
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan/brownish-grey; Luster: Waxy to dull; Crystal structure: Trigonal/Hexagonal microcrystalline; Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan/brownish-grey
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan/brownish-grey; Luster: Waxy to dull; Crystal structure: Trigonal/Hexagonal microcrystalline; Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped by fluvial (river) erosion, causing its rounded, smooth shape.
Uses & applications
Primarily used in landscaping, construction aggregate, and as decorative stone. High-quality quartzite is used as a dimension stone for architecture.
Geological facts
Quartzite is so tough that it often outlasts the original bedrock from which it formed. It is even harder than the steel of a masonry drill bit.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its smooth, water-worn texture if found near water. It lacks the graininess of sandstone and has a more fused, crystalline appearance.
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