metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale (harder than glass); Color: White, gray, or yellow (due to iron impurities); Luster: Vitreous to greasy; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale (harder than glass)
- Color
- White, gray, or yellow (due to iron impurities)
- Luster
- Vitreous to greasy
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale (harder than glass); Color: White, gray, or yellow (due to iron impurities); Luster: Vitreous to greasy; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure. The individual quartz grains recrystallize and fuse together into a dense, interlocking mosaic of crystals. Most deposits range from Proterozoic to Paleozoic eras.
Uses & applications
Used extensively in construction as crushed stone for road ballast, roofing granules, and as a decorative building stone. High-purity quartzite is used in the manufacture of glass and silicon metal.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks, forming prominent ridges and hills (monadnocks). It is often mistaken for marble, but can be distinguished because quartzite will scratch glass while marble will not.
Field identification & locations
Identify in the field by its extreme hardness and 'sugary' crystalline texture on fresh breaks. It is commonly found in mountain ranges and areas with ancient continental crust. Collector tip: look for translucent pieces with interesting iron staining.
More like this
