igneous

Granite (Light-colored quartz/feldspar variety)

Granite (composed primarily of Quartz SiO2 and Feldspar KAlSi3O8)

Hardness: 6-7 on Mohs scale. Color: Speckled white, grey, and black. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). Cleavage: Varies by mineral content; quartz has none, feldspar has two directions.

Hardness: 6-7 on Mohs scale
Color: Speckled white, grey, and black
Luster: Vitreous to dull

Identified April 7, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface (intrusive). This process creates large, visible mineral grains. Geological age varies from Precambrian to Cenozoic.

Uses & applications

Widely used in construction for countertops, floor tiles, paving stone, curbing, and monuments. Also a popular specimen for educational geology kits.

Geological facts

Granite makes up much of the continental crust. It is one of the hardest and most durable natural stones, which is why it has been used since ancient Egypt for colossal statues and pyramids.

Field identification & locations

Identify by its 'salt and pepper' appearance and large interlocking crystals. It is found in mountain ranges and continental shields worldwide. Use a hardness test; it will scratch glass easily.

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