metamorphic
River Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Light gray to tan/greenish hues; Luster: Dull to vitreous; Crystal structure: Trigonal/Hexagonal (granular microcrystalline); Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Light gray to tan/greenish hues
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Light gray to tan/greenish hues; Luster: Dull to vitreous; Crystal structure: Trigonal/Hexagonal (granular microcrystalline); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz sandstone under heat and pressure. This specimen shows significant rounding and smoothing due to fluvial (river) erosion over a long period.
Uses & applications
Used primarily as decorative landscaping stone, in construction aggregates, or as tumbled stones for hobbyist collections.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of hills and ridges because it resists weathering better than surrounding rocks.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its granular, sugary texture on fresh breaks. Very common in riverbeds and glacial deposits worldwide.
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