igneous

Granite

Phaneritic Felsic Igneous Rock

Hardness: 6-7 on Mohs scale; Color: Pink, white, gray, and black speckles; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: None (though constituent minerals like mica and feldspar have cleavage); Specific gravity: 2.63 to 2.75

Hardness: 6-7 on Mohs scale
Color: Pink, white, gray, and black speckles
Luster: Vitreous to dull

Identified March 24, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of silica-rich magma below the Earth's surface. This specimen appears to be 'pink granite' due to high potassium feldspar content, typically dating from various geological eras including the Precambrian to the Cenozoic.

Uses & applications

Major use in construction as dimension stone (countertops, flooring, monuments) and as crushed stone for road base and concrete aggregate. Highly valued for durability and aesthetics.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in the Black Hills of South Dakota.

Field identification & locations

Identify in the field by its visible interlocking crystals of quartz (glassy), feldspar (pink/white blocks), and mica (shiny black flakes). It cannot be scratched by a steel knife. Common in mountainous regions and shield areas like the Canadian Shield.

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