igneous
Granite / Quartz Vein Rock
Granitoid with Quartz (SiO2)
Hardness: 6-7 Mohs; Color: Grey, white, and black mottled; Luster: Vitreous to dull; Crystal structure: Phaneritic (visible crystals); Cleavage: Poor/none.
- Hardness
- 6-7 Mohs
- Color
- Grey, white, and black mottled
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Grey, white, and black mottled; Luster: Vitreous to dull; Crystal structure: Phaneritic (visible crystals); Cleavage: Poor/none.
Formation & geological history
Formed through the slow cooling of silica-rich magma deep underground. Quartz veins often form later when hydrothermal fluids fill fractures in the cooling rock.
Uses & applications
Commonly used in construction, countertops, road base, and as decorative landscaping stone.
Geological facts
Granite makes up a large portion of the Earth's continental crust. These specific pieces show hydrothermal quartz associated with darker mafic minerals.
Field identification & locations
Identify by its 'salt and pepper' appearance and hardness (it will scratch glass). Often found in mountain ranges or glacial till.
