igneous

Granite

Felsic Plutonic Rock (primarily SiO2, Al2O3, K2O, Na2O)

Hardness: 6-7 Mohs; Color: White, gray, or pink with dark specks; Luster: Vitreous to dull; Crystal structure: Phaneritic (medium to coarse-grained), holocrystalline; Cleavage: None (individual crystals like feldspar show cleavage, but rock breaks irregularly); Specific Gravity: 2.63 - 2.75

Hardness: 6-7 Mohs
Color: White, gray, or pink with dark specks
Luster: Vitreous to dull

Identified March 31, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. It is a plutonic rock found in continental crust. Ages range from the Archean Eon to relatively recent Cenozoic formations.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stones, and memorial monuments due to its durability and aesthetic appeal. Also used as crushed stone in road base.

Geological facts

Granite makes up much of the Earth's continental crust. Yosemite National Park's famous Half Dome and El Capitan are massive granite monoliths. It is one of the hardest and most resistant rocks used by humans since ancient Egypt.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and visible interlocked crystals of quartz (clear/gray), feldspar (white/pink), and mica (black/shiny). Common in mountain ranges and shielded areas. Collectors look for specific mineral inclusions or unique coloration.

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