metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Yellowish-orange to honey-colored due to iron staining; Luster: Vitreous to waxy; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Yellowish-orange to honey-colored due to iron staining
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Yellowish-orange to honey-colored due to iron staining; Luster: Vitreous to waxy; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, which causes the sand grains to recrystallize and fuse together. This specimen shows signs of alluvial weathering and smoothing.
Uses & applications
Used as a decorative stone, in construction as crushed stone for road beds or railway ballast, and occasionally for lapidary work as a semi-precious gemstone.
Geological facts
Quartzite is so tough that it often survives intense weathering better than the surrounding rocks. It is harder than a steel knife and will scratch glass easily.
Field identification & locations
Identify in the field by its hardness (will scratch glass) and its sugary or grainy appearance on fresh surfaces despite its overall smoothness. Commonly found in riverbeds, glacial deposits, or mountain belts.
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