igneous

Granite

Granite (Phaneritic Igneous Rock)

Hardness: 6-7 on Mohs scale; Color: Speckled gray, black, and white; Luster: Variable (glassy quartz, pearly feldspar); Crystal structure: Phaneritic (coarse-grained), crystalline; Specific gravity: 2.63 - 2.75.

Hardness: 6-7 on Mohs scale
Color: Speckled gray, black, and white
Luster: Variable (glassy quartz, pearly feldspar)

Identified April 7, 2026More igneous →

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Physical properties

Formation & geological history

Formed by the slow crystallization of magma below Earth's surface. It is a coarse-grained intrusive rock. Common in continental crust and mountain ranges, often dating back hundreds of millions of years.

Uses & applications

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

Geological facts

Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest natural stones available.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. It is common in rocky outcrops 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