igneous

Granite

Granite (Mainly Quartz, Alkali Feldspar, and Plagioclase)

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 component. Specific gravity: 2.63-2.75.

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

Identified May 14, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. It is an intrusive rock typically formed in continental crusts over millions of years.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stone, monuments, 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 in the Black Hills of South Dakota.

Field identification & locations

Identify in the field by its interlocking 'salt and pepper' crystalline texture where minerals are large enough to see with the naked eye. Found globally in mountainous regions and shield areas.

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