igneous

Granite Pebble

Granite (Phaneritic Quartz-Feldspar Rock)

Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, and black. Luster: Dull (weathered) to vitreous (on fresh breaks). Crystal structure: Phaneritic/Coarse-grained. Cleavage: None (though constituent minerals like feldspar have it). Specific gravity: 2.63-2.75.

Hardness: 6-7 on Mohs scale
Color: Mottled pink, white, and black
Luster: Dull (weathered) to vitreous (on fresh breaks)

Identified April 6, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling and solidification of magma below the Earth's surface (intrusive). This specimen shows signs of water erosion (rounding), likely from a river or glacial transport during the Holocene or Pleistocene.

Uses & applications

Larger deposits are used for construction, countertops, and dimension stone. This small pebble is common for landscaping, aquarium gravel, or as a pocket stone for collectors.

Geological facts

Granite makes up the majority of the Earth's continental crust. It is primarily composed of quartz, orthoclase feldspar, and mica or amphibole minerals.

Field identification & locations

Identify by its 'salt and pepper' appearance and visible interlocking crystals. Common in mountain ranges and riverbeds. Look for the presence of pink feldspar and translucent quartz.

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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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

Magnetite

Iron(II,III) oxide (Fe3O4)

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Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

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

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Magnetite

Magnetite (Fe3O4)

mineral