igneous

Granite

Granite (primarily Quartz, Feldspar, and Mica)

Hardness: 6-7 on Mohs scale; Color: Gray, white, or pinkish with dark flecks; Luster: Vitreous to dull; Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (fractures irregularly); Specific gravity: 2.63-2.75.

Hardness: 6-7 on Mohs scale
Color: Gray, white, or pinkish with dark flecks
Luster: Vitreous to dull

Identified April 9, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface (intrusive). Most continental granite was formed during the Precambrian to Paleozoic eras in orogenic belts.

Uses & applications

Extensively used in construction, countertops, monuments, paving stones, and as aggregate for roads.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most durable natural stones.

Field identification & locations

Identify by its interlocking 'salt and pepper' crystalline texture where minerals are large enough to see with the naked eye. Found in mountainous or glaciated regions with exposed bedrock.

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

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral