igneous
Granite
Granite (composed mainly of Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 Mohs; Color: Pink, white, and grey mottled; Luster: Vitreous when polished; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Pink, white, and grey mottled
- Luster
- Vitreous when polished
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Physical properties
Hardness: 6-7 Mohs; Color: Pink, white, and grey mottled; Luster: Vitreous when polished; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. This specimen specifically shows a high concentration of potassium feldspar giving it a pinkish hue. It is an intrusive igneous rock typical of continental crust architecture.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, and monuments. When tumbled as a small specimen, it is used for educational collections and decorative gravel.
Geological facts
Granite is one of the hardest and most durable natural stones, which is why it has been used for monuments like the Egyptian pyramids and Mount Rushmore. The pink color is usually due to the presence of orthoclase feldspar.
Field identification & locations
Identify in the field by its interlocking 'salt and pepper' or multicrystalline texture where individual mineral grains (quartz, feldspar, mica) are visible to the naked eye. Commonly found in mountainous regions or glacial deposits.
