metamorphic
Orange Quartzite (Tumble-polished)
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: Pale orange to honey-yellow; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6 - 2.8
- Hardness
- 7 (Mohs scale)
- Color
- Pale orange to honey-yellow
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale orange to honey-yellow; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6 - 2.8
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone. High heat and pressure cause the original quartz grains to recrystallize into a dense, interlocking mosaic of quartz crystals. Common in old mountain belts and shield regions.
Uses & applications
Used frequently as decorative stones in landscaping, as tumbling rough for hobbyists, in jewelry (beads/cabochons), and industrially as a source of silica or for high-durability construction aggregate.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. It is often more durable than the parent sandstone and forms prominent ridges or weather-resistant outcrops in many mountain ranges.
Field identification & locations
Identify in the field by its grainy, 'sugary' texture and extreme hardness. Unlike calcite-based rocks, it will not fizz in contact with acid. Commonly found in areas with tectonic activity or ancient eroded mountain roots.
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