metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, often with yellow or pink tints; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white to gray, often with yellow or pink tints
- 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: typically white to gray, often with yellow or pink tints; Luster: Vitreous to dull; Crystal structure: Trigonal; 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 into a dense, hard rock. This specimen appears water-worn, likely from a river or beach environment.
Uses & applications
Used extensively in construction as road ballast, gravel, and dimension stone for flooring and walls. High-purity quartzite is used to produce silica sand for glassmaking and industrial abrasives. It is also a popular material for decorative landscaping.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. Unlike sandstone, which breaks around its grains, quartzite breaks through the grains because the crystalline structure is so tightly interlocking.
Field identification & locations
Identify in the field by its extreme hardness and smooth, sugary texture. It is commonly found in mountain ranges or as rounded cobbles in riverbeds. Collectors look for unique color bands or translucent qualities.
More like this
