metamorphic
Gray Quartzite with Quartz Veining
Metamorphosed Quartz-rich Sandstone
Hardness: 7 on Mohs scale; Color: Light to dark gray with white crystalline veins; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Light to dark gray with white crystalline veins
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Light to dark gray with white crystalline veins; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure. The white veins represent hydrothermal quartz that filled fractures in the rock post-metamorphism. Found in ancient mountain belts.
Uses & applications
Primarily used as a durable construction material, road ballast, and occasionally for landscaping or decorative stone due to its weather resistance.
Geological facts
Quartzite is so hard that it will scratch glass and even high-quality steel. It is often tougher than its parent sandstone because the individual grains have fused together.
Field identification & locations
Identify in the field by its grainy, sandpaper-like texture that cannot be rubbed off, and its inability to be scratched by a steel knife. Commonly found in riverbeds or mountainous regions locally.
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