igneous

Granite

Granite (Felsic Plutonic Rock)

Hardness: 6-7 on Mohs scale; Color: Phaneritic (medium-to-coarse grained) mixture of white, gray, pink, and black; Luster: Dull to vitreous; Structure: Massive and granular; Cleavage: None (minerals within have individual cleavage); Specific Gravity: 2.63 to 2.75

Hardness: 6-7 on Mohs scale
Luster: Dull to vitreous

Identified April 11, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface (intrusive). Most continental granite dates from the Precambrian era to the present, forming in magmatic arcs and orogenic belts.

Uses & applications

Used extensively in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.

Geological facts

Granite makes up a large portion of the Earth's continental crust. It is extremely durable and is the reason many mountain ranges, like the Sierra Nevada, remain standing after millions of years of erosion.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. It is found in the cores of mountain ranges and in shield areas of continents.

Other igneous specimens

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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