sedimentary
Quartz Pebble (Iron-stained)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: yellowish-tan due to iron oxide staining; Luster: vitreous to dull; Crystal structure: Hexagonal (though rounded by erosion); Cleavage: none (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- yellowish-tan due to iron oxide staining
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: yellowish-tan due to iron oxide staining; Luster: vitreous to dull; Crystal structure: Hexagonal (though rounded by erosion); Cleavage: none (conchoidal fracture).
Formation & geological history
Formed through the cooling of silica-rich magma or hydrothermal veins. This specific specimen has been chemically weathered and physically eroded into a rounded pebble, likely by fluvial (river) or marine action.
Uses & applications
Common quartz is used in construction as aggregate, in glassmaking, and in electronics for its piezoelectric properties. Pebbles like this are often used in landscaping or as aquarium gravel.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Its yellow or orange color in natural pebbles is usually not its internal color, but a thin coating of limonite or hematite 'rust' from the environment.
Field identification & locations
Identify in the field by its hardness (it can scratch glass and steel) and lack of cleavage. Found globally in riverbeds, beaches, and glacial deposits. High-purity quartz sands are essential for the silicon chip industry.
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