igneous

Granite

Hardness: 6-7 on Mohs scale. Color: Highly variable, commonly pink, white, gray, or black, often mottled. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). No distinct cleavage planes for the rock as a whole, but individual mineral crystals have cleavage. Specific Gravity: 2.6-2.7 g/cm³.

Hardness: 6-7 on Mohs scale
Luster: Vitreous to dull

Identified November 18, 2025More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below the Earth's surface (intrusive igneous). It cools slowly, allowing large crystals to form. It is found in continental crust and is typically very old, often Precambrian to Mesozoic in age.

Uses & applications

Widely used in construction for countertops, flooring, paving, and building facades due to its durability and aesthetic appeal. Also used in monuments, gravestones, and as an aggregate in road construction.

Geological facts

Granite is one of the most common intrusive igneous rocks and forms the core of many mountain ranges. Its name comes from the Latin 'granum', meaning 'grain', referring to its coarse-grained structure. It is a major component of the Earth's continental crust.

Field identification & locations

Identify in the field by its granular, phaneritic texture (visible interlocking crystals), and its composition of quartz (glassy, gray), feldspar (white, pink, or cream, often blocky), and mica (black, shiny flakes) or other dark minerals. Its hardness means it is not easily scratched. Commonly found in mountainous regions, shield areas, and as the basement rock of continents worldwide, such as the Sierra Nevada in the USA or the Scottish Highlands.

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