igneous

Granite

Hardness: 6-7 (Mohs), Color: Pink (orthoclase feldspar), grey (quartz), and black (biotite/hornblende), Luster: Vitreous to dull, Crystal Structure: Phaneritic (coarse-grained, visible crystals), Specific Gravity: 2.63 - 2.75

Identified April 9, 2026More igneous →

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Physical properties

Formation & geological history

Formed by the slow crystallization of magma below Earth's surface (intrusive igneous). It can range from Precambrian to Cenozoic eras and is primarily found in continental crust or mountain ranges.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.

Geological facts

Granite is one of the hardest and most common rocks on Earth's continental crust. The pink color in this specific specimen indicates a high concentration of potassium-rich feldspar.

Field identification & locations

Identify in the field by its speckled appearance and 'salt and pepper' look with visible, interlocking crystals. Common in mountainous regions and tectonic plate boundaries. Use a hand lens to see mineral cleavage in feldspar.

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