metamorphic
Red Quartzite
Quartzite (SiO2 with iron oxide impurities)
Hardness: 7 on Mohs scale; Color: Reddish-pink to brownish-red; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Very durable and dense.
- Hardness
- 7 on Mohs scale
- Color
- Reddish-pink to brownish-red
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-pink to brownish-red; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Very durable and dense.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in orogenic (mountain-building) belts. The red color is caused by the presence of hematite or other iron oxides during formation.
Uses & applications
Used as decorative stone in landscaping, crushed stone for road construction and railway ballast, and occasionally for lapidary work or as architectural facing stone.
Geological facts
Quartzite is so tough that it often survives intense weathering and erosion better than the rocks surrounding it, leading it to form the caps of many ridges and hills. It is harder than steel.
Field identification & locations
Identified in the field by its extreme hardness (cannot be scratched by a steel knife) and its grainy, sugary texture that resembles sandstone but breaks through the grains rather than around them. Common in Precambrian shields.
