metamorphic
Quartzite pebble
Quartzite (mostly Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: White to grey with reddish-brown iron staining or hematite streaks; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.63-2.65.
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: White to grey with reddish-brown iron staining or hematite streaks; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.63-2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been water-worn into a smooth pebble shape, likely in a river or coastal environment during the Quaternary period.
Uses & applications
Commonly used as a decorative stone, in landscaping, as a construction aggregate, and occasionally for lapidary work or as worry stones.
Geological facts
Quartzite is so hard that it will scratch glass and steel. It is much more resistant to weathering than the sandstone it originated from, which is why quartzite pebbles are common in riverbeds.
Field identification & locations
Identify in the field by its hardness (will scratch a knife blade), sugary texture when broken, and lack of reaction to acid. Found globally in mountainous regions and glacial deposits.
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