igneous

Gray Granite

Granite (Phaneritic igneous rock)

Hardness: 6-7 on Mohs scale; Color: Gray, salt-and-pepper appearance; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific gravity: 2.63 to 2.75

Hardness: 6-7 on Mohs scale
Color: Gray, salt-and-pepper appearance
Luster: Vitreous to dull

Identified May 29, 2026More igneous →

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Physical properties

Hardness: 6-7 on Mohs scale; Color: Gray, salt-and-pepper appearance; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific gravity: 2.63 to 2.75

Formation & geological history

Formed from the slow crystallization of silica-rich magma below the Earth's surface (intrusive). They can be hundreds of millions to billions of years old, often found in the cores of mountain ranges.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments due to its durability and resistance to weathering.

Geological facts

Granite is one of the most common rocks on Earth's continental crust. It is often the primary material of famous mountain peaks like El Capitan in Yosemite National Park.

Field identification & locations

Identify by the presence of visible interlocking crystals of quartz (clear/gray), feldspar (white/pink), and mica (black). Commonly found in continental mountain ranges and eroded shield areas.

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