metamorphic
Quartzite River Cobble
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: tan, yellow-brown (iron staining), and gray; Luster: dull to vitreous; Structure: granular/crystalline micro-structure. Smooth, rounded texture due to water erosion.
- Hardness
- 7 (Mohs scale)
- Color
- tan, yellow-brown (iron staining), and gray
- Luster
- dull to vitreous
Identified More metamorphic →
Explore Quartzite River Cobble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: tan, yellow-brown (iron staining), and gray; Luster: dull to vitreous; Structure: granular/crystalline micro-structure. Smooth, rounded texture due to water erosion.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen has been rounded by fluvial processes (river transport) over thousands of years.
Uses & applications
Mainly used as decorative garden stones, construction aggregate, or landscaping rock. High-purity quartzite is used in the glass and chemical industries.
Geological facts
Quartzite is so tough that it often resists weathering better than other rocks, frequently capping hills and ridges. The yellow-brown bands on this stone are caused by iron oxide (limonite) staining within the silica matrix.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its lack of reaction to acid. Often found in riverbeds, glacial tills, or ancient sedimentary basins.
More like this
