igneous

Granite Thin Section

Granitic rock (Phaneritic texture)

Hardness: 6-7 Mohs; Color: Interstitial quartz (white/gray), feldspars (tan/brown), and micas (high-interference 'bird-eye' maple colors); Luster: Vitreous under thin section; Structure: Crystalline mosaic; Cleavage: Visible in feldspar grains.

Hardness: 6-7 Mohs
Luster: Vitreous under thin section

Identified May 3, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow cooling and crystallization of felsic magma deep within the Earth's crust (plutonic). Found in continental crust contexts, often dating from the Precambrian to Cenozoic eras.

Uses & applications

Used primarily for geological study and petrography to identify mineral assemblages. In bulk form, granite is used for construction, countertops, and monuments.

Geological facts

This image is captured through a petrographic microscope using cross-polarized light (XPL), which causes minerals to display vibrant interference colors based on their birefringence properties.

Field identification & locations

Identify by presence of quartz (low relief, undulatory extinction), plagioclase (twinning), and biotite or muscovite. Found in mountain ranges and batholiths worldwide.

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

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral