metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, but can be brownish/yellow due to impurities; Luster: vitreous to granular; Crystal structure: Trigonal (as quartz); Cleavage: none, conchoidal fracture; Specific gravity: 2.6 - 2.7.
- Hardness
- 7 on Mohs scale
- Luster
- vitreous to granular
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: typically white to gray, but can be brownish/yellow due to impurities; Luster: vitreous to granular; Crystal structure: Trigonal (as quartz); Cleavage: none, conchoidal fracture; Specific gravity: 2.6 - 2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together into a dense, interlocking matrix. It is found in mountain belts and areas of regional metamorphism globally.
Uses & applications
Used in construction as crushed stone for road ballast, floor coverings, and wall facing. Pure varieties are used to produce silica sand for glassmaking and industrial abrasives. Highly durable for outdoor landscaping.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, forming prominent ridges and hills. Unlike sandstone, which breaks around grains, quartzite breaks through the grains.
Field identification & locations
Identify by its extreme hardness (it will easily scratch glass and steel) and its crystalline, sugary appearance. Found in ancient mountain roots. Collectors look for translucent or unusually colored specimens.
More like this
