metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on the Mohs scale. Color: White to tan/sand colored. Luster: Vitreous to dull. Texture: Granular, sugary appearance when broken. Cleavage: None (conchoidal fracture).
- Hardness
- 7 on the Mohs scale
- Color
- White to tan/sand colored
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on the Mohs scale. Color: White to tan/sand colored. Luster: Vitreous to dull. Texture: Granular, sugary appearance when broken. Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events (orogeny). Common in Precambrian formations.
Uses & applications
Used as crushed stone in construction, road ballast, and as a raw material for glass making. High-purity quartzite is used to produce ferrosilicon and silicon metal.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during weathering, forming prominent ridges and peaks in mountainous terrain.
Field identification & locations
Identify in the field by its inability to be scratched by a steel nail and its lack of reaction to acid (unlike limestone). Commonly found in riverbeds as rounded 'river rocks' due to erosion resistance.
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