igneous
Granitoid (Common Granite)
Intrusive Igneous Granite-type Rock
Hardness: 6-7 (Mohs scale); Color: Mottled white, pink, grey with black inclusions; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific Gravity: 2.63 to 2.75
- Hardness
- 6-7 (Mohs scale)
- Color
- Mottled white, pink, grey with black inclusions
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled white, pink, grey with black inclusions; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific Gravity: 2.63 to 2.75
Formation & geological history
Formed by the slow cooling of silica-rich magma deep beneath the Earth's surface (plutonic). This specific specimen appears to be a water-worn river stone or glacial cobble, rounded by erosion over millions of years.
Uses & applications
Used extensively in construction (countertops, tiles, paving), monuments, and as crushed stone for road aggregate. Smooth cobbles like this are often used in landscaping.
Geological facts
Granite makes up a large portion of the Earth's continental crust. It is exceptionally durable and resistant to weathering compared to other rock types.
Field identification & locations
Identified in the field by its speckled appearance of interlocking quartz and feldspar crystals. It is commonly found in mountain ranges and glaciated plains across North America and Europe.
