metamorphic
Quartzite
Quartzite (SiO2 silicon dioxide)
Hardness: 7 (Mohs scale); Color: Grayish-tan, yellow-brown due to impurities; Luster: Vitreous to waxy; Texture: Granular, smooth from water-tumbling; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
- Hardness
- 7 (Mohs scale)
- Color
- Grayish-tan, yellow-brown due to impurities
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-tan, yellow-brown due to impurities; Luster: Vitreous to waxy; Texture: Granular, smooth from water-tumbling; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure. This specimen is a stream-worn pebble, likely from the Quaternary period or older depending on the parent formation.
Uses & applications
Used in construction for road ballast, floor tiles, and as a decorative stone. High-purity quartzite is also used to produce silica sand for glass manufacturing.
Geological facts
Quartzite is one of the most physically durable and chemically resistant rocks on the Earth's surface. It is often mistake for quartz, but quartzite is a rock composed of many interlocking quartz grains rather than a single crystal.
Field identification & locations
Identify in the field by its hardness (will easily scratch glass) and its sugary, granular look under a hand lens. Commonly found in riverbeds, glacial tills, and mountain ranges.
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