metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: grayish-white with tan/orange iron staining; Luster: vitreous to waxy; Structure: granoblastic, microcrystalline; Cleavage: none (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- grayish-white with tan/orange iron staining
- Luster
- vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: grayish-white with tan/orange iron staining; Luster: vitreous to waxy; Structure: granoblastic, microcrystalline; Cleavage: none (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, often during mountain-building events. This specific specimen has been further smoothed by fluvial (river) or glacial transport.
Uses & applications
Used as a decorative landscape stone, abrasive, or in construction as high-quality aggregate. Polished versions are used in lapidary for low-cost jewelry or aquarium stones.
Geological facts
Quartzite is one of the most durable rocks on Earth, surviving long after the softer rocks surrounding it have eroded away. It is often harder than the steel blades of tools used to mine it.
Field identification & locations
Identify in the field by its ability to scratch glass and lack of reaction to acid. Often found in riverbeds or beaches where water has rounded the jagged edges of broken metamorphic rock.
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