metamorphic
Red Quartzite
Quartzite (Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: Reddish-orange to brown due to iron oxide inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- Reddish-orange to brown due to iron oxide inclusions
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-orange to brown due to iron oxide inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.63-2.65
Formation & geological history
Formed through the metamorphism of quartz sandstone. High pressure and heat cause the quartz grains to recrystallize and fuse together, often incorporating iron-rich minerals that provide the red hue.
Uses & applications
Used in construction for railway ballast, decorative stone in landscaping, crushed stone for road building, and occasionally as a semi-precious stone for lapidary work.
Geological facts
Quartzite is so tough that it often survives the weathering process better than the rocks surrounding it, leading to the formation of quartzite ridges and hills. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a steel blade) and its granular, sugary texture that resembles sandstone but will break through the grains rather than around them. Found globally in ancient mountain belts.
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