igneous
Granite featuring Quartz Vein
Granite with hydrothermal silica (SiO2) intrusion
Hardness: 6-7 Mohs; Color: Gray, salt-and-pepper, with a translucent milky-white to brown vein; Luster: Dull to vitreous (on the vein); Crystal Structure: Phaneritic (granular); Cleavage: None (conchoidal fracture on quartz); Specific Gravity: 2.6-2.7
- Hardness
- 6-7 Mohs
- Luster
- Dull to vitreous (on the vein)
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Physical properties
Hardness: 6-7 Mohs; Color: Gray, salt-and-pepper, with a translucent milky-white to brown vein; Luster: Dull to vitreous (on the vein); Crystal Structure: Phaneritic (granular); Cleavage: None (conchoidal fracture on quartz); Specific Gravity: 2.6-2.7
Formation & geological history
Granite forms from the slow cooling of magma beneath the Earth's surface (plutonic). The vein observed formed later via hydrothermal processes, where mineral-rich hot water filled fissures in the cooling rock, crystallizing as quartz.
Uses & applications
Used widely in construction as crushed stone or dimension stone (countertops/monuments). Quartz veins are of interest to prospectors as they often contain precious metals like gold.
Geological facts
Granite makes up much of the Earth's continental crust. These veins are like 'scars' or 'fillings' in the rock, representing fluid movement throughout the geological history of the area.
Field identification & locations
Identify in the field by its speckled 'salt and pepper' appearance and the presence of a distinct, lighter-colored mineral band cutting across the grain. Found in continental mountain ranges and shield areas.
