metamorphic
Quartzite with Mica schist fragment
Quartzite (SiO2) with Muscovite/Biotite Schist
Hardness: 7 (quartz) to 2.5 (mica); Color: Grey, tan, off-white; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal; Cleavage: None in quartz, perfect one-way in mica.
- Hardness
- 7 (quartz) to 2
- Color
- Grey, tan, off-white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 7 (quartz) to 2.5 (mica); Color: Grey, tan, off-white; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal; Cleavage: None in quartz, perfect one-way in mica.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone. Under intense heat and pressure, quartz grains recrystallize into a dense network. The presence of schistose layers suggests a parent rock with some clay or silt content.
Uses & applications
Quartzite is used heavily in construction as crushed stone or decorative building stone. Schist has limited use but can be found in floor tiles or wall coverings.
Geological facts
Quartzite is so durable that it can outlast the mountains it creates through erosion, often forming the tops of ridges and peaks.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary texture under a lens. Commonly found in ancient mountain belts or glacial till.
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