metamorphic
Red Quartzite
Quartzite (SiO2 with iron oxide inclusions)
Hardness: 7 (Mohs scale), Color: Rusty red to brownish-red with pale interior, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: Rusty red to brownish-red with pale interior, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone. High pressure and heat cause quartz grains to recrystallize and fuse together. The red color is typically due to hematite or other iron oxides present during formation.
Uses & applications
Used in construction for road ballast, as a decorative stone in landscaping, and sometimes as a minor gemstone or for lapidary work.
Geological facts
Quartzite is so tough that it often survives intense weathering and glacial transport, ending up as rounded river or glacial cobbles over millions of years. It is harder than steel.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its coarse, sugary texture on fresh breaks. It is commonly found in mountain belts and glacial till.
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