metamorphic
Quartzite (with possible Iron staining)
Meta-orthoquartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Tan, yellowish-brown with dark surface patches; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, yellowish-brown with dark surface patches
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, yellowish-brown with dark surface patches; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone subjected to high heat and pressure, recrystallizing the original quartz grains into a dense, interlocking mosaic of crystals.
Uses & applications
Commonly used as crushed stone in road construction, as railway ballast, and occasionally as decorative stone or in the glass manufacturing industry if high purity is maintained.
Geological facts
Quartzite is so durable that it can outlast the mountains from which it is derived; it is often found as rounded cobbles in riverbeds long after softer rocks have eroded away.
Field identification & locations
Identify in the field by its hardness (it should easily scratch glass) and its sugary, granular texture. It will not react to acid like limestone would. Often found in mountainous regions or glacial deposits.
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