metamorphic
Orange Quartzite
Quartzite (SiO2 with iron oxide impurities)
Hardness: 7 on Mohs scale; Color: Orange to reddish-brown; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None; Fracture: Conchoidal to irregular; High specific gravity (2.6-2.7).
- Hardness
- 7 on Mohs scale
- Color
- Orange to reddish-brown
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Orange to reddish-brown; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None; Fracture: Conchoidal to irregular; High specific gravity (2.6-2.7).
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure. The orange hue is caused by the inclusion of hematite or other iron oxides during the burial process.
Uses & applications
Used primarily as decorative stone, crushed stone for road construction, railroad ballast, and in landscaping. Polished versions are used in jewelry and lapidary art.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, frequently forming the tops of ridges and mountains. It is harder than steel and will scratch a glass plate.
Field identification & locations
Identify by its ability to scratch glass and its sugary, crystalline texture on a fresh break. Commonly found in metamorphic belts and as stream-rounded pebbles in areas with ancient bedrock.
