igneous

Granite Water-Worn Pebble

Phaneritic Felsic Igneous Rock

Hardness: 6-7 on Mohs scale. Color: Mottled pink, grey, and black. Luster: Vitreous to dull. Crystal Structure: Phaneritic (visible crystals of quartz, feldspar, and mica). Specific Gravity: 2.63-2.75.

Hardness: 6-7 on Mohs scale
Color: Mottled pink, grey, and black
Luster: Vitreous to dull

Identified June 3, 2026More igneous →

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Physical properties

Formation & geological history

Formed by the slow cooling of silica-rich magma deep underground, typically during the Precambrian or Paleozoic eras. This specific specimen has been rounded and smoothed by water erosion in a river or beach environment.

Uses & applications

Larger deposits are used for countertops, construction, and monuments. Small pebbles are used for landscaping, decorative aquariums, and rock tumbling hobbies.

Geological facts

Granite makes up a large portion of the Earth's continental crust. The pink color in this specimen is specifically caused by Potassium Feldspar (Orthoclase).

Field identification & locations

Identify by the 'salt and pepper' appearance and visible interlocking crystals. Common in glacial till and riverbeds across North America and Europe. Look for a mix of translucent quartz and opaque feldspar.

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Granite

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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