metamorphic
Green Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Pale green to olive; Luster: Vitreous/greasy; Crystal structure: Trigonal/Hexagonal (microcrystalline); Specific gravity: 2.6 - 2.8; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Pale green to olive
- Luster
- Vitreous/greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Pale green to olive; Luster: Vitreous/greasy; Crystal structure: Trigonal/Hexagonal (microcrystalline); Specific gravity: 2.6 - 2.8; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure reciprocal to deep burial or tectonic activity cause quartz grains to recrystallize and fuse. The green tint is typically caused by inclusions of minerals like fuchsite or chlorite.
Uses & applications
Used in construction as decorative stone, crushed stone for road beds, and for jewelry/lapidary work. It is also used as a source of silica in glass manufacturing.
Geological facts
Quartzite is so tough that it often survives intense weathering better than the rocks surrounding it, leading to the formation of prominent ridges and hilltops in many mountain ranges.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel blade) and its granular, sugary texture on freshly broken surfaces. Common in many Precambrian shields like the Canadian Shield or the Appalachians.
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