metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: tan, white, or light gray; Luster: vitreous to dull; Crystal structure: hexagonal (within grains); Cleavage: none; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- tan, white, or light gray
- 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, white, or light gray; Luster: vitreous to dull; Crystal structure: hexagonal (within grains); Cleavage: none; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing sand grains to recrystallize and fuse together.
Uses & applications
Used in construction as crushed stone for road beds, in glass making as a source of silica, and as a decorative stone in landscaping or countertops.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks, forming ridges and mountain peaks. It can be distinguished from sandstone because it fractures through the grains rather than around them.
Field identification & locations
Identify in the field by its hardness (scratches glass) and its sugary, granular texture. Common in ancient mountain belts and as water-worn pebbles in riverbeds or beaches.
