igneous

Granite

Granite (Mainly Quartz, Feldspar, and Mica)

Hardness: 6-7 on Mohs scale. Color: White, pink, or gray with mottled dark spots. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, visible crystals). Cleavage: Varies by mineral inside (Feldspar has good cleavage, Quartz has none). Specific Gravity: 2.63 to 2.75.

Hardness: 6-7 on Mohs scale
Color: White, pink, or gray with mottled dark spots
Luster: Vitreous to dull

Identified March 22, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below the Earth's surface (intrusive). Most common in continental crust, with some formations dating back billions of years to the Precambrian era.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stones, and monuments. Also used as crushed stone for road base and railroad ballast.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Famous natural landmarks like Mount Rushmore and Yosemite's Half Dome are composed almost entirely of granite. It is one of the hardest and most durable common stones.

Field identification & locations

Identify in the field by its 'salt and pepper' look and crystalline texture where individual grains of quartz and feldspar are visible to the naked eye. Found globally in mountain ranges and shields. Collectors look for large crystals 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

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral