metamorphic
Ferruginous Quartzite (Red Quartzite)
Quartzite with Hematite inclusions (SiO2 + Fe2O3)
Hardness: 7 (Mohs scale); Color: Red-brown to rusty orange; Luster: Dull to vitreous; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Red-brown to rusty orange
- Luster
- Dull to vitreous
Identified More metamorphic →
Explore Ferruginous Quartzite (Red Quartzite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: Red-brown to rusty orange; Luster: Dull to vitreous; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. The high heat and pressure recrystallize quartz grains into a dense, interlocking mosaic. The red color comes from iron oxide (hematite) staining of the original sand grains or groundwater infiltration.
Uses & applications
Used primarily as decorative stone, aquarium rocks, landscaping material, and crushed stone for road construction due to its extreme durability and hardness.
Geological facts
Quartzite is so tough that it often survives intense erosion better than the surrounding rocks, frequently forming the tops of ridges and hills. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sandpaper-like texture that has been 'sealed' shut. Common in ancient shields like the Canadian Shield and the Appalachian Mountains. Look for it in riverbeds where its hardness allows it to remain as rounded cobbles.
More like this
