metamorphic
Quartzite / Sandstone
Quartzite (SiO2-rich metamorphic rock)
Hardness: 6.5-7 on Mohs scale; Color: Tan, brown, gray, reddish-brown; Luster: Dull to vitreous; Texture: Granular, fine- to medium-grained; Cleavage: None (conchoidal to irregular fracture).
- Hardness
- 6
- Color
- Tan, brown, gray, reddish-brown
- Luster
- Dull to vitreous
Identified More metamorphic →
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Tan, brown, gray, reddish-brown; Luster: Dull to vitreous; Texture: Granular, fine- to medium-grained; Cleavage: None (conchoidal to irregular fracture).
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone under intense heat and pressure, or as heavily weathered ferruginous sandstone.
Uses & applications
Used as construction aggregate, ballast, decorative landscaping stone, and occasionally in stone tools historically.
Geological facts
Quartzite is extremely durable and resistant to both chemical and physical weathering, often forming prominent ridge tops in mountain ranges.
Field identification & locations
Field identification involves testing hardness (scratches glass easily) and looking for a sugary, interlocked crystalline granular texture that doesn't break easily along grain boundaries. Commonly found in mountainous regions, riverbeds, and glacial deposits.
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