metamorphic
Quartzite
Quartzite (SiO2)
Hardness (Mohs): 7. Color: Greyish-green to white. Luster: Vitreous/grainy. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.63 - 2.65.
- Color
- Greyish-green to white
- Luster
- Vitreous/grainy
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Physical properties
Hardness (Mohs): 7. Color: Greyish-green to white. Luster: Vitreous/grainy. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.63 - 2.65.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together into a dense, interlocking structure.
Uses & applications
Used as a decorative stone, in construction as crushed stone or road ballast, and in the manufacturing of glass and ceramics due to high silica content.
Geological facts
Quartzite is so tough that it often breaks through the individual quartz grains rather than around them. This particular specimen shows a characteristic sugary texture and slight greenish tint likely from trace minerals like chlorite.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by steel) and its grainy, sandpaper-like texture that sparkles under light. Commonly found in folded mountain belts.
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