metamorphic
Quartzite Pebble
Quartzite (SiO2 with iron oxide inclusions)
Hardness: 7 on Mohs scale; Color: reddish-orange to brownish-orange due to hematite/iron staining; Luster: dull to vitreous; Texture: granular, microcrystalline; Specific Gravity: ~2.65
- Hardness
- 7 on Mohs scale
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: reddish-orange to brownish-orange due to hematite/iron staining; Luster: dull to vitreous; Texture: granular, microcrystalline; Specific Gravity: ~2.65
Formation & geological history
Formed from the metamorphism of quartz sandstone under heat and pressure, where quartz grains recrystallize into an interlocking matrix. Smoothly rounded through fluvial or beach erosion.
Uses & applications
Landscaping, decorative garden pebbles, aquarium gravel, aggregate in construction, and lapidary tumbling.
Geological facts
Quartzite is so hard that when it breaks, it fractures through the individual quartz grains rather than along the boundaries between them, unlike its precursor sandstone.
Field identification & locations
Identified by its extreme hardness (scratches glass easily), granular crystalline texture, and well-rounded stream-worn pebble shape. Commonly found in riverbeds, glacial deposits, and coastal beaches.
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