metamorphic
Green Quartzite
Metamorphosed Quartz-Arenite (SiO2)
Hardness: 7 on Mohs scale; Color: Pale green to grey-green; Luster: Vitreous to dull; Crystal structure: Hexagonal/Triggered crystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Pale green to grey-green
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Pale green to grey-green; Luster: Vitreous to dull; Crystal structure: Hexagonal/Triggered crystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, often in orogenic (mountain-building) belts.
Uses & applications
Used in construction as crushed stone or dimension stone, abrasive applications, and occasionally for lapidary work or aquarium decor.
Geological facts
Quartzite is so tough that it often survives intense weathering better than the rocks surrounding it, forming prominent ridges and peaks in mountain ranges.
Field identification & locations
Identify by its extreme hardness (it will easily scratch steel and glass) and its sugary, crystalline texture that breaks through the grains rather than around them. Common in the Appalachian Mountains and Canadian Shield.
