metamorphic
Red Quartzite
Quartzite (mostly SiO2)
Hardness: 7 (Mohs scale), Color: Reddish-brown to maroon, Luster: Vitreous to dull, Crystal Structure: Trigonal (granular), Cleavage: None, Fracture: Conchoidal to splintery
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Physical properties
Hardness: 7 (Mohs scale), Color: Reddish-brown to maroon, Luster: Vitreous to dull, Crystal Structure: Trigonal (granular), Cleavage: None, Fracture: Conchoidal to splintery
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure. The red color is typically caused by tiny inclusions of hematite (iron oxide).
Uses & applications
Used as decorative stone, crushed stone for road construction, railway ballast, and in some architectural masonry.
Geological facts
Quartzite is so tough that it often outlasts the surrounding softer rocks, forming the backbone of many major mountain ranges. The red variety is specifically prized for its aesthetic appeal in lapidary work.
Field identification & locations
Identified by its extreme hardness (cannot be scratched by a steel knife) and its grainy, sandpaper-like texture that lacks the visible pore space of sandstone. Commonly found in metamorphic belts worldwide.
