metamorphic
Quartzite
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: Brownish-tan to orange-yellow; Luster: Vitreous to waxy (when polished by water); Crystal Structure: Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Brownish-tan to orange-yellow
- Luster
- Vitreous to waxy (when polished by water)
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: Brownish-tan to orange-yellow; Luster: Vitreous to waxy (when polished by water); Crystal Structure: Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. Under intense heat and pressure, quartz grains recrystallize and fuse together, creating a hard, dense rock. Most specimens date from the Proterozoic to Paleozoic eras.
Uses & applications
Used in construction as road ballast, gravel, and flooring. Highly weathered or polished river stones are used in landscaping and interior decor. Historically used for making stone tools.
Geological facts
Quartzite is so strong that when it breaks, the fracture passes through the quartz grains rather than along the boundaries between them, unlike its parent sandstone.
Field identification & locations
Identify in the field by its hardness (will scratch glass) and lack of reaction to acid. Often found in riverbeds or glacial deposits as rounded cobbles. Found globally in mountainous or formerly glaciated regions.
More like this
