metamorphic
Orange Quartzite
Quartzite (primarily SiO2 with Hematite impurities)
Hardness: 7 on Mohs scale; Color: Pinkish-orange to reddish-brown; Luster: Vitreous to waxy; Structure: Granular/Granoblastic; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-orange to reddish-brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Pinkish-orange to reddish-brown; Luster: Vitreous to waxy; Structure: Granular/Granoblastic; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together. The orange hue is typically caused by the inclusion of iron oxides (hematite) during formation.
Uses & applications
Used as decorative stone, railway ballast, aggregates in construction, and occasionally for lapidary work like cabochons or tumbled stones for metaphysical use.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during weathering, frequently forming the caps of hills and ridges. It is often confused with marble, but unlike marble, it will not fizz when exposed to acid.
Field identification & locations
Identification involves checking hardness (it will scratch glass) and looking for a sugary, granular texture where the original sand grains have fused. Commonly found in folded mountain belts like the Appalachians or the Scottish Highlands.
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