igneous

Granite

Granite (Felsic Plutonic Rock)

Hardness: 6-7 Mohs; Color: White/grey background with pink (orthoclase) and dark (biotite/hornblende) inclusions; Luster: Vitreous to dull; Crystal structure: Phaneritic (visible crystals); Specific gravity: 2.63 to 2.75

Hardness: 6-7 Mohs
Luster: Vitreous to dull

Identified May 6, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling and crystallization of molten magma deep beneath the Earth's surface (plutonic). Found in continental crust, often appearing in mountain roots or shield areas, dating back to various geological eras from the Precambrian to Cenozoic.

Uses & applications

Extensively used in construction for countertops, floor tiles, and grave markers due to its durability. Smaller polished specimens are popular for rock tumbling and as decorative 'pocket stones'.

Geological facts

Granite is the most common igneous rock found at the Earth's surface and makes up a significant portion of the continental crust. The pink spots in this specimen are likely Potassium Feldspar (Orthoclase).

Field identification & locations

Identify by its 'salt and pepper' or multi-colored speckled appearance and extreme hardness (cannot be scratched by a steel knife). Commonly found in glaciated areas as 'river rocks' or in mountain outcrops.

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