igneous
Granite
Phaneritic Plutonic Felsic Rock (Granite)
Hardness: 6-7 on Mohs scale; Color: Pinkish-red (orthoclase feldspar) with gray/white (quartz) and dark specks; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Perfect in feldspars, none in quartz; Specific gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pinkish-red (orthoclase feldspar) with gray/white (quartz) and dark specks; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Perfect in feldspars, none in quartz; Specific gravity: 2.63 to 2.75.
Formation & geological history
Formed through the slow cooling and crystallization of silica-rich magma deep underground. Most granitic formations date back to the Precambrian or Paleozoic eras, found in continental crust within batholiths.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base and railroad ballast.
Geological facts
Granite makes up the core of most continental plates. The pink color in this specific specimen is due to a high concentration of potassium feldspar (orthoclase). It is one of the hardest and most durable common rocks on Earth.
Field identification & locations
Identify in the field by its interlocking coarse crystals of pink feldspar and glassy gray quartz. Common in mountain ranges and Canadian Shield areas. Collectors look for large crystals or unique coloration.
