igneous
Pink Granite (Alkali Feldspar Granite)
Phaneritic Plutonic Felsic Rock (SiO2, KAlSi3O8, NaAlSi3O8)
Hardness: 6-7 Mohs; Color: Pink, salmon, or reddish-orange due to potassium feldspar; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 Mohs
- Color
- Pink, salmon, or reddish-orange due to potassium feldspar
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Pink, salmon, or reddish-orange due to potassium feldspar; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63 to 2.75
Formation & geological history
Formed by the slow crystallization of silica-rich magma deep underground (plutonic). The pink hue indicates a high concentration of orthoclase (potassium feldspar). Found in continental crust from various eras, frequently dating to the Precambrian or Paleozoic.
Uses & applications
Massively used in construction for countertops, floor tiles, and monuments. It is favored for outdoor curbs and decorative landscaping due to its durability and resistance to weathering.
Geological facts
Mount Rushmore is carved into a granite batholith. The pink variety is specifically prized for architectural aesthetics. Its crystals are large enough to be seen with the naked eye because it cooled very slowly over thousands of years.
Field identification & locations
Identify by its interlocking 'salt and pepper' crystalline texture and distinct pink hue. It will scratch glass but not be scratched by a steel knife. Common in continental shields like the Canadian Shield or the Scottish Highlands.
