igneous

Pink Granite Porphyry Cobble

Porphyritic K-Feldspar Granite

Hardness: 6-7 (Mohs scale); Color: Pink to tan matrix with visible red, black, and white phenocrysts; Luster: Dull to vitreous; Crystal structure: Phaneritic/Porphyritic; Cleavage: Good in feldspars, none in quartz; Specific gravity: 2.63 - 2.75

Hardness: 6-7 (Mohs scale)
Luster: Dull to vitreous

Identified May 28, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of silica-rich magma deep underground, allowing larger crystals (phenocrysts) to form before the surrounding matrix crystallized. This specific specimen has been rounded through fluvial or glacial transport.

Uses & applications

Used primarily in landscaping, construction as aggregate, and decorative river rock. Polished varieties are used in countertops and monuments.

Geological facts

Granite is the primary component of the Earth's continental crust. Porphyritic textures suggest a two-stage cooling process where the magma cooled slowly first, then more rapidly as it moved closer to the surface.

Field identification & locations

Identify by its interlocking crystalline texture and pink/salmon color (due to Potassium Feldspar) with distinct larger mineral grains 'floating' in a finer-grained crystalline mass. Common in glacial till and riverbeds throughout North America.

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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

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Magnetite

Iron(II,III) oxide (Fe3O4)

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Blue Apatite

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Sodalite

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