igneous
Quartz Vein in Schist / Gneiss
Silicon Dioxide (SiO2) in Metamorphic Matrix
Hardness: 7 (Quartz on Mohs scale), Color: Milky white to reddish-pink quartz with brown and grey metamorphic host rock, Luster: Vitreous to greasy on quartz surfaces, Crystal Structure: Trigonal quartz crystals embedded in foliated matrix, Cleavage: None in quartz (conchoidal fracture), Specific Gravity: ~2.65
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Physical properties
Hardness: 7 (Quartz on Mohs scale), Color: Milky white to reddish-pink quartz with brown and grey metamorphic host rock, Luster: Vitreous to greasy on quartz surfaces, Crystal Structure: Trigonal quartz crystals embedded in foliated matrix, Cleavage: None in quartz (conchoidal fracture), Specific Gravity: ~2.65
Formation & geological history
Formed when silica-rich hydrothermal fluids circulated through fractures in deeply buried metamorphic host rocks (such as schist or gneiss) during regional metamorphism, crystallizing into milky quartz veins.
Uses & applications
Used primarily as a decorative specimen, landscape stone, and occasionally crushed for industrial silica or aggregate. Quartz veins can also be indicators for precious metal mineralization like gold.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Massive quartz veins often host valuable ore deposits because the hot fluids that deposited the quartz also carried dissolved metals like gold and copper.
Field identification & locations
Identified by the distinct contrast between coarse, hard milky quartz (which easily scratches glass) and the darker, foliated or layered schist/gneiss host rock surrounding it. Commonly found in metamorphic terrains worldwide.
