metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with pinkish or dark inclusions; Luster: Vitreous to dull/sugary; Crystal Structure: Granular/Massive; Cleavage: None (breaks across grains)
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with pinkish or dark inclusions
- Luster
- Vitreous to dull/sugary
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with pinkish or dark inclusions; Luster: Vitreous to dull/sugary; Crystal Structure: Granular/Massive; Cleavage: None (breaks across grains)
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the original quartz grains to recrystallize and fuse together into a dense, hard framework.
Uses & applications
Used in construction as crushed stone for road ballast, as a decorative building stone, and historically for stone tools due to its hardness and durability.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, forming ridges and mountains. It can sometimes be mistaken for marble, but it is much harder and will not react to acid.
Field identification & locations
Identify by its hardness (it scratches glass easily) and granular texture. Look for it in glaciated riverbeds or mountain ranges where tectonic activity has occurred.
