igneous

Granite Water-Worn Pebble

Granite (composed primarily of Quartz, Feldspar, and Mica)

Hardness: 6-7 Mohs; Color: Salt and pepper appearance with gray, translucent quartz, pinkish-tan feldspar, and black biotite/mica flecks; Luster: Vitreous to dull; Crystal structure: Phaneritic (visible grains); Specific gravity: 2.63-2.75

Hardness: 6-7 Mohs
Luster: Vitreous to dull

Identified June 2, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of silica-rich magma deep underground (plutonic formation). This specific specimen has been smoothed and rounded by river or beach water erosion over thousands of years.

Uses & applications

Used in construction, countertops, and landscaping. Small polished pebbles are used in decorative gravel, aquariums, and rock tumbling kits.

Geological facts

Granite is the primary rock making up the Earth's continental crust. It is one of the hardest and most durable common stones, which is why it resists weathering better than surrounding rocks.

Field identification & locations

Identify by its multi-colored, crystalline texture where individual grains of quartz and feldspar are visible. It will scratch glass and won't react with acid. Commonly found in riverbeds and mountainous regions.

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Granite

Igneous

Granite

Igneous

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dalmatian Jasper

Aplite with Arfvedsonite inclusions

igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

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