metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None; Specific Gravity: 2.6 – 2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or tan
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None; Specific Gravity: 2.6 – 2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone under intense heat and pressure, causing quartz grains to recrystallize and fuse.
Uses & applications
Used in construction as crushed stone or decorative facing, in manufacturing of glass and ceramics, and as a durable material for countertops and flooring.
Geological facts
Quartzite is so hard that it can scratch glass. It is often confused with marble, but unlike marble which fizzes with acid, quartzite is chemically inert to acid.
Field identification & locations
Identify in the field by its extreme hardness and sugary, crystalline texture; it breaks across grainy boundaries rather than around them. Found globally in mountainous regions and riverbeds as smoothed pebbles like this specimen.
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