mineral
Quartz (Milky or Iron-stained)
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale), Color: White to tan/yellowish (due to iron staining), Luster: Vitreous to greasy, Crystal structure: Trigonal, Cleavage: None (conchoidal fracture)
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Physical properties
Hardness: 7 (Mohs scale), Color: White to tan/yellowish (due to iron staining), Luster: Vitreous to greasy, Crystal structure: Trigonal, Cleavage: None (conchoidal fracture)
Formation & geological history
Formed in hydrothermal veins or pegmatites; extremely common in continental crust. This specimen likely weathered from a quartz vein within granite or schist.
Uses & applications
Industrial use in glassmaking, abrasives, electronics (piezoelectric properties), and as a gemstone or collector specimen.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to chemical and physical weathering, which is why it often remains as pebbles after other minerals have eroded away.
Field identification & locations
Identify by its hardness (it will easily scratch glass) and lack of cleavage. Found globally in almost all geological environments.
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