metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, brown, or light grey; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.63-2.65.
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, or light grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, or light grey; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.63-2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure over millions of years. This pebble has been weathered and rounded by water action, likely in a river or glacial deposit.
Uses & applications
Commonly used as construction aggregate, road ballast, landscaping stone, and occasionally as a source of silica in glass manufacturing.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. It is one of the most durable rocks on Earth, which is why it often survives as a pebble long after other rocks have eroded away.
Field identification & locations
Identify in the field by its hardness and its granular, sugary texture that resembles sandpaper but is smooth to the touch. Found globally in riverbeds, beaches, and glacial till.
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