metamorphic
Red Quartzite (Ferruginous Quartz)
Quartzite (SiO2 with Fe2O3 inclusions)
Hardness: 7 (Mohs scale), Color: Rusty red to orange-brown with translucent white areas, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Rusty red to orange-brown with translucent white areas, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together. The red coloration is due to the presence of iron oxide (hematite) staining during or after formation.
Uses & applications
Used as decorative stone in landscaping, aquarium gravel, as a gemstone for tumbling/cabochons, and as crushed stone for construction and road base due to its extreme durability.
Geological facts
Quartzite is so hard that it will scratch glass and steel. It is often more durable than its parent rock, sandstone, and is highly resistant to chemical weathering.
Field identification & locations
Identify by its extreme hardness and grainy texture that looks like sandpaper but feels smooth to the touch. Found globally in mountainous regions where tectonic activity has occurred.
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