metamorphic
Ferruginous Quartzite
Quartzite with Hematite/Limonite inclusions (SiO2)
Hardness: 7 (Mohs scale); Color: Reddish-brown, orange, and tan due to iron oxides; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None; Specific Gravity: 2.6 - 2.8
- Hardness
- 7 (Mohs scale)
- Color
- Reddish-brown, orange, and tan due to iron oxides
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Reddish-brown, orange, and tan due to iron oxides; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None; Specific Gravity: 2.6 - 2.8
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. The distinct red and orange coloration results from the oxidation of iron-bearing minerals (like hematite or goethite) within the original sediment or introduced via groundwater.
Uses & applications
Primarily used as crushed stone in road construction and rail ballast. Distinctive colored specimens are popular for decorative landscaping and as aquarium stones.
Geological facts
Quartzite is one of the most durable and weather-resistant rocks on Earth. Ferruginous varieties are often mistaken for jasper, but quartzite has a grainier, more crystalline texture when viewed closely.
Field identification & locations
Identify in the field by its inability to be scratched by a steel blade and its granular, sandpaper-like texture. Commonly found in ancient mountain belts and shield areas such as the Lake Superior region and various parts of the Appalachian Mountains.
