metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: Pinkish-red to tan; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-red to tan
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Pinkish-red to tan; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure from tectonic activity, individual quartz grains recrystallize and fuse into a dense, hard rock. This specimen shows water-worn rounding, likely from a riverbed or coastal environment.
Uses & applications
Used primarily in construction as crushed stone or ballast. Rounded pebbles are often used in landscaping, decorative ground cover, and as tools in lapidary work.
Geological facts
Quartzite is so tough that it often survives long-term erosion better than the rocks around it, resulting in resistant ridges or rounded river pebbles that can travel miles from their source.
Field identification & locations
Identify in the field by its hardness (it can scratch glass) and its sugary texture on fresh breaks. It is found globally in areas of ancient mountain building. For collectors, look for unique colors or water-smoothed shapes.
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