igneous
Granitoid (Pegmatitic Granite)
Granitoid with dominant Potassium Feldspar and Quartz
Hardness: 6-7 Mohs; Color: Pink, grey, and white; Luster: Vitreous to pearly; Crystal structure: Phaneritic to pegmatitic (large crystals); Cleavage: Perfect cleavage in feldspar bits, none in quartz; Specific gravity: 2.6-2.7
- Hardness
- 6-7 Mohs
- Color
- Pink, grey, and white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-7 Mohs; Color: Pink, grey, and white; Luster: Vitreous to pearly; Crystal structure: Phaneritic to pegmatitic (large crystals); Cleavage: Perfect cleavage in feldspar bits, none in quartz; Specific gravity: 2.6-2.7
Formation & geological history
Formed by the slow cooling of silica-rich magma deep within the Earth's crust, often in the late stages of magma crystallization where mineral crystals have space and time to grow large.
Uses & applications
Used in construction, as decorative stone, countertops, and as a source for minerals like feldspar and quartz for industrial ceramics and glass.
Geological facts
Granite makes up a large portion of the Earth's continental crust. These specific specimens show distinct 'pockets' of pink orthoclase feldspar and greyish smoky quartz.
Field identification & locations
Identify by the presence of large mineral grains that interlock. Common in mountainous regions and shield areas like the Canadian Shield or the Appalachians. Look for the characteristic 'salt and pepper' or 'pink and grey' chunky appearance.
