metamorphic
Blue Quartzite
Quartzite (SiO2 with mineral inclusions)
Hardness: 7 on Mohs scale; Color: Pale blue to sky blue with tan/oxidized inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Pale blue to sky blue with tan/oxidized inclusions
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Pale blue to sky blue with tan/oxidized inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Specific gravity: 2.6-2.7.
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. The blue color often results from Rayleigh scattering of light by microscopic inclusions of other minerals like dumortierite or magnetite.
Uses & applications
Used as a decorative gemstone, in cabochons for jewelry, as a healing crystal in metaphysical practices, and occasionally as dimension stone for high-end architecture.
Geological facts
Unlike blue quartz which is an igneous mineral, blue quartzite is a metamorphic rock. It is often confused with blue calcite, but quartzite is much harder and will easily scratch glass.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by a steel knife) and its grainy, crystalline texture that breaks across the grains rather than around them. Common in metamorphic belts in Brazil, India, and the USA.
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