igneous

Granite

Plutonic felsic igneous rock

Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, black); Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained coarse crystals of quartz, feldspar, and mica); Specific Gravity: 2.63-2.75.

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

Identified April 5, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. It is a major component of the continental crust and can be billions of years old.

Uses & applications

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

Geological facts

Granite is one of the hardest substances in the world, second only to diamonds. It makes up the core of many mountain ranges like the Sierra Nevada.

Field identification & locations

Identify by its interlocking 'mosaic' of visible crystals. It is found globally in continental shields and mountain belts. Collectors look for unique mineral inclusions like garnet or tourmaline.

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