metamorphic
Quartzite Cobble
Quartzite (Silicon Dioxide: SiO2)
Mohs hardness: 7; Color: Pinkish-tan/orange (likely due to iron oxidation); Luster: Vitreous to waxy; Structure: Granular/crystalline; Cleavage: None/conchoidal fracture; Specific gravity: 2.63–2.65.
- Hardness
- 7
- Color
- Pinkish-tan/orange (likely due to iron oxidation)
- Luster
- Vitreous to waxy
Identified More metamorphic →
Explore Quartzite Cobble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness: 7; Color: Pinkish-tan/orange (likely due to iron oxidation); Luster: Vitreous to waxy; Structure: Granular/crystalline; Cleavage: None/conchoidal fracture; Specific gravity: 2.63–2.65.
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. This specimen appears water-worn, indicating it was transported by a river or glacial meltwater.
Uses & applications
Used as a construction aggregate, railway ballast, and in some cases as an abrasive or for landscaping. Highly durable and resistant to weathering.
Geological facts
Quartzite is so hard and durable that it often survives where other rocks weather away. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify by its hardness (scratches glass), sugary-granular appearance on fresh surfaces, and lack of reaction to acid. Often found as rounded 'river stones' or cobbles in glacial till across North America and Europe.
More like this
