igneous

Granite

Granite (Alkali-feldspar granite)

Hardness (Mohs scale): 6 to 7. Color: Gray, white, pink, or red with speckled dark spots. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). Cleavage: Imperfect. Specific gravity: 2.63 to 2.75.

Color: Gray, white, pink, or red with speckled dark spots
Luster: Vitreous to dull

Identified May 28, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below the Earth's surface during various geological periods. Found in continental crust, specifically in batholiths and mountainous regions.

Uses & applications

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

Geological facts

Granite is one of the hardest substances in the world. It makes up a large portion of the Earth's continental crust and is often millions to billions of years old.

Field identification & locations

Identify by its interlocking 'salt and pepper' appearance of quartz, feldspar, and mica. Commonly found in glacial deposits or mountainous outcrops. Collectors look for unique mineral patterns or rare colors.

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