metamorphic
Orange Quartzite
Quartzite (primarily SiO2 with hematite or iron oxide inclusions)
Hardness: 7 on Mohs scale; Color: Orange to reddish-pink; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.63–2.65.
- Hardness
- 7 on Mohs scale
- Color
- Orange to reddish-pink
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Orange to reddish-pink; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.63–2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing quartz grains to recrystallize and fuse. The orange hue is typically due to iron oxide staining during or after formation.
Uses & applications
Used as decorative stone in landscaping, jewelry (as tumbled stones or cabochons), construction aggregate, and in glassmaking if pure enough.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, often forming the caps of hills and ridges. It is harder than steel and can scratch glass easily.
Field identification & locations
Identify in the field by its sugary texture on broken surfaces and its extreme hardness (cannot be scratched by a knife). Commonly found in ancient mountain belts and glacial till.
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