sedimentary
Milky Quartz Pebble with Iron Inclusions
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 7 (Mohs scale), Color: cloudy white to pinkish-orange due to staining, Luster: vitreous to waxy, Crystal structure: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: cloudy white to pinkish-orange due to staining, Luster: vitreous to waxy, Crystal structure: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed in hydrothermal veins or pegmatites initially (igneous/metamorphic), but this specific specimen has been rounded by water transport in a stream or river environment (alluvial deposition). Age varies widely depending on source bedrock.
Uses & applications
Used as decorative gravel, in landscaping, as tumbling rough for hobbyists, and in some contexts as a source of silica for industrial manufacturing.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Specimens like this are often called 'river rocks' and acquire their smooth shape over thousands of years of tumbling in riverbeds.
Field identification & locations
Identified by its hardness (it will scratch glass), its smooth water-worn surface, and its resistance to chemical weathering. Found globally in riverbeds, beaches, and glacial deposits.
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