metamorphic
Quartzite with Iron Inclusions
Quartzite (primarily SiO2 with Fe2O3 impurities)
Hardness: 7 (Mohs scale); Color: White, grey, and rusty brown; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- White, grey, and rusty brown
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: White, grey, and rusty brown; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. The iron staining (brown areas) occurs via secondary oxidation or mineral infiltration.
Uses & applications
Used in construction as crushed stone, for road ballast, floor tiles, and in decorative landscaping or as garden stones.
Geological facts
Quartzite is so hard that it can scratch glass and steel easily. It is one of the most durable rocks on the Earth's surface and often forms the resistant caps of many mountain ranges.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a knife) and its grainy, 'sugary' texture. Common in ancient mountain belts and riverbeds as rounded cobbles.
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