metamorphic
Red Quartzite / Ferruginous Quartz
Quartzite (primarily Silicon Dioxide, SiO2 with Iron Oxide impurities)
Hardness: 7 on Mohs scale. Color: Reddish-brown to pink due to hematite/iron staining. Luster: Vitreous to dull. Structure: Granular, non-foliated. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown to pink due to hematite/iron staining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale. Color: Reddish-brown to pink due to hematite/iron staining. Luster: Vitreous to dull. Structure: Granular, non-foliated. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together. The red color comes from iron oxide (hematite) present during or after formation.
Uses & applications
Used in construction as crushed stone or road ballast, as decorative landscaping stone, and occasionally for lapidary work like tumbling or cabochon making.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges it was part of, frequently appearing as smooth, rounded cobbles in riverbeds or beaches because it resists chemical weathering.
Field identification & locations
Identify by its ability to scratch glass and its granular, crystalline texture. It will not react with acid (unlike marble). Commonly found in ancient mountain belts and glacial till.
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