metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: White to light grey with iron staining; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None, breaks with conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- White to light grey with iron staining
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light grey with iron staining; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None, breaks with conchoidal fracture.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. Geological age varies widely from Precambrian to Cenozoic.
Uses & applications
Used as a decorative stone in landscaping, as railway ballast, in road construction, and due to its high silica content, sometimes in glass and ceramic production.
Geological facts
Quartzite is so tough that it often forms the capstone of mountain ranges because it resists erosion much better than surrounding rocks like shale or limestone.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary appearance despite being very hard. Commonly found in folded mountain belts globally. Unlike limestone, it will not fizz with acid.
