igneous

Granite Pebble

Granite (composed primarily of Quartz SiO2, Feldspar KAlSi3O8, and Biotite/Hornblende)

Hardness: 6-7 (Mohs scale), Color: Pink, orange, white and black mottled pattern, Luster: Vitreous when polished, Crystal structure: phaneritic (granular), Clavage: Indistinct, Specific gravity: 2.63 - 2.75

Identified May 28, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below the Earth's surface during the Precambrian to Cenozoic eras. This specific specimen appears to be water-worn into a smooth pebble shape.

Uses & applications

Commonly used in construction, countertops, and abrasive materials; polished pebbles like this are used for landscaping, aquarium decor, and pocket stones.

Geological facts

Granite is the most common igneous rock found on Earth's continents. It is the building block of many famous mountain ranges like the Sierra Nevada and the Himalayas.

Field identification & locations

Identify in the field by its 'salt and pepper' or mottled appearance with visible interlocking crystals of different colors. It is frequently found in riverbeds and glacial deposits.

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

Dalmatian Jasper

Aplite with Arfvedsonite inclusions

igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral