igneous

Granite Pebble

Granite (Phaneritic intrusive igneous rock consisting of Quartz, Alkali Feldspar, and Plagioclase)

Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (mottled grey, white, and black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Specific gravity: 2.63 - 2.75

Hardness: 6-7 on Mohs scale
Color: Salt-and-pepper (mottled grey, white, and black)
Luster: Vitreous to dull

Identified February 24, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. This specific specimen shows signs of mechanical weathering and erosion, likely in a riverbed or coastal environment, which rounded its edges over thousands of years.

Uses & applications

Commonly used as construction aggregate, road base, or decorative landscaping stones. Larger slabs are used for countertops and monuments.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Because it is very hard and resistant to acid rain, it is the preferred material for outdoor statues and gravestones.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and the presence of interlocking crystals of quartz and feldspar. Found globally in mountainous regions or as glacial till and river gravel in lower elevations.

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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)

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