igneous
Red Granite
Phaneritic Felsic Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 Mohs; Color: Pinkish-red to deep reddish-brown; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Perfect in feldspars, none in quartz; Specific Gravity: 2.63 - 2.75
- Hardness
- 6-7 Mohs
- Color
- Pinkish-red to deep reddish-brown
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Pinkish-red to deep reddish-brown; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Perfect in feldspars, none in quartz; Specific Gravity: 2.63 - 2.75
Formation & geological history
Formed through the slow cooling of silica-rich magma deep underground. The red color is typically caused by the presence of potassium feldspar (orthoclase) and may be enhanced by trace amounts of hematite iron oxide. Geological age varies by location from Precambrian to Cenozoic.
Uses & applications
Extensively used in construction as dimension stone, kitchen countertops, monuments, curbing, and decorative landscaping. High-quality red variants are popular for gravestones and architectural cladding.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Famous examples of red granite include the Aswan Granite used in Ancient Egyptian obelisks and the 'Texas Red' granite used for the Texas State Capitol.
Field identification & locations
Identify in the field by its interlocking mineral crystals and granular texture. Look for visible glassy quartz and pink/red rectangular feldspar crystals. It is found in mountain ranges and continental shields worldwide.
