igneous
Granite (Alkali-feldspar rich)
Phaneritic Felsic Igneous Rock (Major components: KAlSi3O8, SiO2)
Hardness: 6-7 on Mohs scale; Color: Pinkish-orange (orthoclase), translucent grey (quartz), and black (biotite); Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained) crystalline; Cleavage: Two directions at 90 degrees in feldspar grains; Specific gravity: 2.63 - 2.75
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pinkish-orange (orthoclase), translucent grey (quartz), and black (biotite); Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained) crystalline; Cleavage: Two directions at 90 degrees in feldspar grains; Specific gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow cooling and crystallization of silica-rich magma deep underground (plutonic) over millions of years. This specimen appears to be a weathered pebble likely from the Precambrian or Paleozoic eras depending on regional source.
Uses & applications
Used extensively in construction for countertops, floor tiles, and curbing. Finely crushed granite is used as road base. Polished specimens are popular for interior design and ornamental masonry.
Geological facts
Granite makes up a large portion of the Earth's continental crust. The pink color in this specific specimen is caused by potassium feldspar (orthoclase), which gets its hue from trace amounts of iron within the crystal lattice.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals. It will not be scratched by a steel knife. Common in mountainous regions with exposed batholiths. For collectors, look for high-contrast mineral separation.
