metamorphic
Quartzite
Quartzite (containing SiO2)
Hardness: 7 on Mohs scale; Color: brownish-tan (likely due to iron oxide staining); Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- brownish-tan (likely due to iron oxide staining)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: brownish-tan (likely due to iron oxide staining); Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); 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. This specimen shows a weathered, granular texture indicating it was part of a larger sedimentary transport system.
Uses & applications
Used in construction as crushed stone or decorative building stone, in the manufacture of glass and ceramics, and as a ballast for railways.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the ridges and peaks of mountain ranges because it resists weathering much better than the rocks around it.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its granular, sugary texture that resembles sandstone but will break through the quartz grains rather than around them. Found globally in ancient mountain belts.
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