metamorphic
Quartzite
Quartzite (SiO2 silicon dioxide)
Hardness: 7 on Mohs scale; Color: typically white to gray but can be pink or red due to iron oxides; Luster: vitreous to dull; Crystal structure: hexagonal (trigonal); Grainy, sandpaper-like surface but very durable.
- Hardness
- 7 on Mohs scale
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray but can be pink or red due to iron oxides; Luster: vitreous to dull; Crystal structure: hexagonal (trigonal); Grainy, sandpaper-like surface but very durable.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, eliminating most of the original sedimentary textures.
Uses & applications
Used extensively in road construction, as railway ballast, in the manufacture of glass and ceramics, and as a decorative stone in architecture and landscaping.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. In some ancient cultures, it was used to create stone tools because of its durability, similar to flint.
Field identification & locations
Identified by its extreme hardness and the fact that it breaks across original sand grains rather than around them. Found globally in mountainous regions where tectonic activity has occurred.
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