igneous
Granite
Granite (Felsic Intrusive Igneous Rock)
Hardness: 6-7 on Mohs scale. Color: Mottled pink, grey, and black. Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained crystals). Cleavage: Varies by mineral component (perfect for mica, poor for quartz). Specific gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled pink, grey, and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Mottled pink, grey, and black. Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained crystals). Cleavage: Varies by mineral component (perfect for mica, poor for quartz). Specific gravity: 2.63 to 2.75.
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface. It is a plutonic rock found in continental crust. This specific specimen appears to be a water-worn pebble or glacial erratic.
Uses & applications
Widely used in construction for countertops, floor tiles, paving stones, curbing, and monuments. Also used as crushed stone for road bases.
Geological facts
Granite makes up a large part of the continental crust. The pink color in this specimen comes from potassium feldspar (orthoclase). It is one of the hardest and most durable common rocks.
Field identification & locations
Identify in the field by its coarse 'salt and pepper' or mottled appearance with visible interlocking crystals of quartz, feldspar, and mica. It is found globally in mountain ranges and shield areas. Collectors value specimens with unique mineral inclusions or large crystals.
