metamorphic
Quartzite
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: yellowish-tan with dark inclusions; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- yellowish-tan with dark inclusions
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: yellowish-tan with dark inclusions; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.63-2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen shows signs of river-worn tumbling.
Uses & applications
Used primarily as masonry, crushed stone for road construction, railway ballast, and occasionally as decorative landscaping stone.
Geological facts
Quartzite is so hard that it will scratch glass and steel. Most quartzite is over 90 percent quartz by volume. It is often more resistant to weathering than the rocks around it, often forming ridges.
Field identification & locations
Identify in the field by its hardness and granular, sugary appearance on a fresh break. Common in glacial till, riverbeds, and ancient metamorphic belts worldwide.
