metamorphic
Quartzite
SiO2 (Silicon Dioxide)
Hardness: 7 on Mohs scale; Color: Tan, off-white, to pale orange; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan, off-white, to pale orange
- Luster
- Vitreous to dull
Identified More metamorphic →
Explore Quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: Tan, off-white, to pale orange; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.65
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together, typically in mountain-building (orogenic) zones.
Uses & applications
Used in construction as crushed stone or ballast, in high-end countertops, as a source of silica for glassmaking, and frequently as a decorative landscaping stone.
Geological facts
Quartzite is so durable that it often stays behind as high ridges when softer rocks erode away. It is distinguishable from its parent rock, sandstone, because it will break across the sand grains rather than around them.
Field identification & locations
Identify by its ability to scratch glass and its grainy, granular texture that looks like sugar. Common in ancient shields such as the Canadian Shield and along riverbeds where erosion has rounded the cobbles.
