metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: white/grey; Luster: vitreous to grainy; Crystal structure: hexagonal (internal microcrystals); Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- white/grey
- Luster
- vitreous to grainy
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: white/grey; Luster: vitreous to grainy; Crystal structure: hexagonal (internal microcrystals); Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone. Under intense heat and pressure, the sand grains recrystallize and fuse together. These formations can date back to any geological age from Precambrian to Cenozoic.
Uses & applications
Used extensively in construction as crushed stone for road ballast, as a dimension stone for flooring and wall coverings, and in the glass-making industry due to high silica content.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in mountain ranges, forming prominent ridges. Unlike sandstone, which breaks around the grains, quartzite breaks through the grains.
Field identification & locations
Identify in the field by its hardness (it will scratch glass easily) and its sugary, sparkling appearance. Commonly found in folded mountain belts like the Appalachians or the Alps. Collectors look for pieces with unique mineral staining.
More like this
