metamorphic
Quartzite with Quartz Vug
Metamorphosed Quartz-rich Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: Rusty brown, tan, and grey with white crystalline patches; Luster: Vitreous to dull; Crystal structure: Trigonal (in vugs); Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Rusty brown, tan, and grey with white crystalline patches
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Rusty brown, tan, and grey with white crystalline patches; Luster: Vitreous to dull; Crystal structure: Trigonal (in vugs); Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during tectonic plate collisions. The crystalline voids (vugs) form from secondary hydrothermal fluid precipitation.
Uses & applications
Mainly used as a decorative stone, in construction as crushed stone or road ballast, and in some cases as an abrasive or in glass manufacturing.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the tops of ridges and mountains because it resists weathering better than surrounding rocks.
Field identification & locations
Identify in the field by its inability to be scratched by a steel pocket knife and its sugary, granular texture that looks like sandpaper but feels smooth. Found globally in ancient mountain belts.
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