metamorphic
Quartzite
Metamorphosed Quartz Sandstone
Hardness: 7 on Mohs scale; Color: typically white to gray, often pink or reddish due to iron oxides; Luster: vitreous to dull; Crystal Structure: non-foliated, granular; Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- 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: typically white to gray, often pink or reddish due to iron oxides; Luster: vitreous to dull; Crystal Structure: non-foliated, granular; Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together into a dense, interlocking matrix. It is found in mountain belts and Precambrian terrains worldwide.
Uses & applications
Used as crushed stone for road construction, railway ballast, and as a decorative building stone. Highly pure varieties are used to produce silica for glassmaking and silicon industrial products.
Geological facts
Quartzite is so tough that it often survives intense weathering and erosion to form the tops of many large mountain ridges. Unlike sandstone, when broken, quartzite fractures across the original sand grains rather than around them.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass) and a sugary, grainy appearance that does not rub off. Look for a conchoidal or splintery fracture pattern where grains are fused together.
More like this
