igneous

Granite

Granite (composed primarily of Quartz SiO2, Feldspar (KAlSi3O8), and Mica)

Hardness: 6-7 on Mohs scale; Color: Gray, white, pink, or speckled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (though constituent minerals like mica have perfect cleavage); Specific gravity: 2.63 to 2.75

Hardness: 6-7 on Mohs scale
Color: Gray, white, pink, or speckled
Luster: Vitreous to dull

Identified March 12, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface (intrusive). Most granites date from the Precambrian to Cenozoic eras, typically found in continental crust and mountain ranges.

Uses & applications

Used extensively in construction for countertops, floor tiles, paving stones, curbing, and monuments. It is also a popular specimen for educational geology kits.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith, and Yosemite’s Half Dome is a famous granite monolith.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz and feldspar. Found globally in mountainous regions or areas where ancient rock is exposed. Use a hand lens to see the glassy quartz and opaque feldspar blocks.

Other igneous specimens

See all

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral