metamorphic
Quartz Vein in Greenstone
Hydrothermal Quartz (SiO2) with Chlorite/Epidote Schist host rock
Hardness: Quartz is 7 on Mohs scale, host matrix is ~5-6. Color: White, milky quartz contrasting with dull olive green and dark brown to black mineral inclusions. Luster: Vitreous to greasy on quartz, dull on metamorphic matrix. Cleavage: None in quartz (conchoidal fracture), poor to moderate in host rock.
- Hardness
- Quartz is 7 on Mohs scale, host matrix is ~5-6
- Luster
- Vitreous to greasy on quartz, dull on metamorphic matrix
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Physical properties
Hardness: Quartz is 7 on Mohs scale, host matrix is ~5-6. Color: White, milky quartz contrasting with dull olive green and dark brown to black mineral inclusions. Luster: Vitreous to greasy on quartz, dull on metamorphic matrix. Cleavage: None in quartz (conchoidal fracture), poor to moderate in host rock.
Formation & geological history
Formed via hydrothermal activity where silica-rich hot water fluids filled fractures in altered mafic volcanic rock (greenstone/metabasalt) or schist during regional metamorphism.
Uses & applications
Primarily of interest to mineral collectors, students, and rockhounds. High-purity quartz veins can sometimes be mined as sources of industrial quartz or indicator rocks for gold mineralization.
Geological facts
Quartz veins hosted in greenstone belts are classic geological environments for lode gold deposits (mesothermal or orogenic gold systems).
Field identification & locations
Look for sharp, contrasting contacts between bright white crystalline quartz and dull green/grey altered mafic volcanic host rock. Commonly found in eroded metamorphic terrains, riverbeds, and ancient volcanic mountain belts.
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