igneous

Granite

Granite (Felsic Plutonic Rock)

Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (white, gray, black, pink). Luster: Dull to vitreous. Crystal structure: Phaneritic (large, visible crystals including quartz, feldspar, and mica). Specific gravity: 2.63 - 2.75.

Hardness: 6-7 on Mohs scale
Color: Salt-and-pepper (white, gray, black, pink)
Luster: Dull to vitreous

Identified April 10, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface (intrusive). Most granite formations date back to the Precambrian or Paleozoic eras, occurring in continental crust and mountain ranges.

Uses & applications

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

Geological facts

Granite makes up a large part of the continental crust. Because it is very hard and resistant to erosion, it often forms the core of many mountain ranges, such as the Sierra Nevada and the Himalayas.

Field identification & locations

Identify by its interlocking 'salt and pepper' crystalline texture where individual minerals are clearly visible. Commonly found in large mountain massifs (plutons). Collectors should look for unique mineral inclusions like tourmaline or large feldspar phenocrysts.

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