igneous

Granite Pebble

Felsic intrusive igneous rock

Hardness: 6-7 on Mohs scale; Color: typically white, gray, or pink with dark specks; Luster: vitreous to dull; Crystal structure: phaneritic (visible crystals of quartz, feldspar, and mica); Specific gravity: 2.63 to 2.75

Hardness: 6-7 on Mohs scale
Color: typically white, gray, or pink with dark specks
Luster: vitreous to dull

Identified May 9, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of silica-rich magma deep underground. This specific specimen has been polished and rounded by water erosion (fluvial or beach action). Geological age varies by location, often millions to billions of years old.

Uses & applications

Used widely in construction (countertops, flooring), road gravel, and as decorative landscaping stones.

Geological facts

Granite makes up a large part of the Earth's continental crust. Over 80% of the Earth's crust is made of igneous rock, and granite is the most common of these. The dark specks are usually biotite mica or hornblende.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals. Common in mountainous regions, riverbeds, and glacial deposits. Very common 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