igneous

Granite (Weathered/Oxidized)

Phaneritic Felsic Igneous Rock (composed of Quartz, Orthoclase Feldspar, and Mica)

Hardness: 6-7 Mohs; Color: Mottled orange-brown (from iron oxidation), gray, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Distinct in feldspar grains, none in quartz.

Hardness: 6-7 Mohs
Color: Mottled orange-brown (from iron oxidation), gray, and black
Luster: Vitreous to dull

Identified March 17, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface (intrusive). The orange/brown staining is due to chemical weathering and the oxidation of iron-bearing minerals, often occurring over millions of years.

Uses & applications

Used widely in construction as dimension stone, aggregates, and countertops. Weathered specimens like this are primarily used for road base, landscaping, or as geological teaching tools.

Geological facts

Granite makes up a large portion of the Earth's continental crust. The pink or orange hue in this specific specimen is likely Limonite or Hematite staining on the potassium feldspar grains.

Field identification & locations

Identify in the field by its 'salt and pepper' crystalline texture and its inability to be scratched by a steel knife. Commonly found in mountainous regions or shield areas like the Appalachians or the Rockies.

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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)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral