igneous

Granite

Granite (composed primarily of Quartz SiO2 and Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8))

Hardness: 6-7 (Mohs scale); Color: Salt and pepper (white, grey, and black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.65-2.75.

Hardness: 6-7 (Mohs scale)
Color: Salt and pepper (white, grey, and black)
Luster: Vitreous to dull

Identified May 15, 2026More igneous →

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Physical properties

Hardness: 6-7 (Mohs scale); Color: Salt and pepper (white, grey, and black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.65-2.75.

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. It is a coarse-grained intrusive rock usually associated with continental crust formation over millions of years.

Uses & applications

Used extensively in construction for countertops, floor tiles, paving stones, and monuments due to its durability and aesthetic appeal.

Geological facts

Granite is one of the hardest substances in the world, second only to diamonds. It makes up a large part of the continental crust and is vital in understanding the movement of tectonic plates.

Field identification & locations

Identify in the field by its speckled 'salt and pepper' look and interlocked visible crystals. It is found in mountain ranges and continental shields. 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)

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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

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Magnetite

Magnetite (Fe3O4)

mineral