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)

Identified April 10, 2026More igneous →

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Physical properties

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.

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