igneous

Granite

Granite (Phaneritic Igneous Rock)

Hardness: 6-7 (Mohs Scale); Color: Salt and pepper (white, gray, pink, black); Lustre: Dull to vitreous; Structure: Phaneritic (large visible crystals); Specific gravity: 2.63-2.75

Hardness: 6-7 (Mohs Scale)
Color: Salt and pepper (white, gray, pink, black)

Identified May 29, 2026More igneous →

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Physical properties

Hardness: 6-7 (Mohs Scale); Color: Salt and pepper (white, gray, pink, black); Lustre: Dull to vitreous; Structure: Phaneritic (large visible crystals); Specific gravity: 2.63-2.75

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface (intrusive). Composed mainly of quartz, feldspar, and mica. Geological ages vary from Precambrian to Cenozoic.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stones, monuments, and as crushed stone for road base and concrete aggregate.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in South Dakota.

Field identification & locations

Identify by looking for visible crystals of different colors (clear quartz, white/pink feldspar, dark mica/amphibole). Common in mountainous regions and glacial deposits.

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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