metamorphic
Quartzite Pebble
Metamorphosed Quartz-rich Sandstone (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Tan, brown, or light orange due to iron staining; Luster: Vitreous to dull; Structure: Granoblastic (sugary texture); Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, or light orange due to iron staining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, or light orange due to iron staining; Luster: Vitreous to dull; Structure: Granoblastic (sugary texture); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the metamorphism of quartz-rich sedimentary sandstone (protolith) under intense heat and pressure, causing the sand grains to recrystallize and fuse together. These pebbles are often smoothed by water erosion in rivers or glacial deposits.
Uses & applications
Primarily used as landscaping stone, construction aggregate, and occasionally as decorative garden stones. Due to its hardness, it is sometimes used for industrial abrasives.
Geological facts
Quartzite is so tough that it often breaks through the constituent sand grains rather than around them. This specific specimen has been naturally eroded into a unique heart-like shape with a small decorative void (vug).
Field identification & locations
Identify by its ability to scratch glass and its sugary, crystalline texture that lacks the visible bedding planes of sandstone. Common in glacial till, riverbeds, and mountainous regions like the Appalachians or the Rockies.
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