metamorphic
Quartzite with Iron Inclusions
Metamorphosed Quartz-rich Rock (SiO2 with Fe2O3)
Hardness: 7 on Mohs scale; Color: Milky white to tan with brownish-orange iron staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Milky white to tan with brownish-orange iron staining
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Milky white to tan with brownish-orange iron staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. The iron staining occurs when groundwater rich in iron minerals permeates the rock surfaces over time.
Uses & applications
Used primarily as decorative landscaping stone, crushed stone for road construction, and occasionally for lapidary work if the staining creates attractive patterns.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the crests of ridges and hills. It is often confused with marble, but can be distinguished because quartzite will not react to acid and is much harder than steel.
Field identification & locations
Look for a granular, sugary appearance on fresh breaks and high hardness (it will easily scratch glass). Found globally in metamorphic belts; iron-stained specimens like this are common in riverbeds and glacial tills.
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