igneous

Granodiorite

Granodiorite (Intermediate plutonic rock)

Hardness: 6-7 (Mohs scale); Color: Salt and pepper (mottled grey, black, and white); Luster: Phaneritic (crystalline); Crystal structure: Coarse-grained; Specific gravity: 2.6-2.7

Hardness: 6-7 (Mohs scale)
Color: Salt and pepper (mottled grey, black, and white)
Luster: Phaneritic (crystalline)

Identified April 10, 2026More igneous →

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Physical properties

Hardness: 6-7 (Mohs scale); Color: Salt and pepper (mottled grey, black, and white); Luster: Phaneritic (crystalline); Crystal structure: Coarse-grained; Specific gravity: 2.6-2.7

Formation & geological history

Formed through the slow cooling of silica-rich magma beneath the Earth's surface in batholiths and mountain-building regions. Common in continental crust and subduction zones.

Uses & applications

Used primarily in heavy construction, road base, and as decorative dimension stone (countertops/monuments). Often sold as 'white granite' in trade.

Geological facts

Granodiorite was the stone used to carve the famous Rosetta Stone. It is the most common rock type in the Sierra Nevada Batholith.

Field identification & locations

Identify by its 'salt and pepper' look with visible crystals of white plagioclase, grey quartz, and black biotite/hornblende. It contains more plagioclase than orthoclase feldspar.

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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