metamorphic
Quartzite with Hematite
Silica (SiO2) with Ferric Oxide (Fe2O3) inclusions
Hardness: 7 (Mohs); Color: Greenish-grey with reddish-brown staining; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture.
- Hardness
- 7 (Mohs)
- Color
- Greenish-grey with reddish-brown staining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs); Color: Greenish-grey with reddish-brown staining; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure, often within orogenic (mountain-building) belts. The red color suggests the infiltration of hematite-rich fluids.
Uses & applications
Used primarily as crushed stone for road construction, railway ballast, and as a decorative stone in landscaping or lapidary arts (cabochons).
Geological facts
Quartzite is so tough that it often breaks through the individual quartz grains rather than around them. The red staining is a common indicator of iron oxidation, sometimes called 'desert varnish' when found on surfaces.
Field identification & locations
Identify in the field by its extreme hardness (will scratch glass) and its sugary, crystalline texture on fresh breaks. Frequently found in mountainous regions or ancient shield areas.
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