metamorphic
Quartzite (River Pebble)
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan/brown with dark streaks; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Tan/brown with dark streaks
- Luster
- Vitreous to dull
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: Tan/brown with dark streaks; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone subjected to high heat and pressure. This specific specimen has been rounded and smoothed by fluvial (water) erosion.
Uses & applications
Used in construction as a decorative stone, road ballast, and in some industrial glass-making. This river-rolled form is popular in landscaping.
Geological facts
Quartzite is so tough that it often resists weathering better than the rocks surrounding it, leading it to cap hills and mountains. It can scratch glass and steel easily.
Field identification & locations
Identify by its extreme hardness and grainy, sugary texture under a lens. Found globally in riverbeds and glacial deposits. Common in regions with ancient mountain belts.
More like this
