State by State


  • Specimen Number


  • Description

    Block of roughly quarried gray granite with pink alkali feldspars.  Verified by Maine Geological Survey.  Crimson-colored stains blotch the rock in the vicinity of pink feldspars but grow over other crystals.

  • Classification

    Igneous. Plutonic. Granitic. Granite.

  • Location & Occurrence

    Likely from Aroostook County because that name is carved on the county's icon, a potato carved into the specimen.  But the rock is common enough to have been collected from many places in Maine and other states.  The state survey was reluctant to suggest a specific source.   Mount Katahdin, a laccolith intrusion of granite located in Aroostook county,  is underlain by such rock, and is thus a plausible source.

  • Geological Age

    Acadian orogeny, with widely scattered dates from 388-414 Ma (USGS source below)

  • Geoheritage

    Plausibly from Katahdin Granite, core of northern Appalachians, the rock on which Henry D. Thoreau experienced a widely known epiphany about the role of humans in the universe.  Nearby Millinocket was reportedly the fastest growing city in the US in the 1930s.

  • Links

    Link to State Geological Map from USGS.  Link to Maine Geological Survey.  Link to USGS describing Katahdin.

  • Other

    Quoting the Hartford Courant 1937, specimen 17  is a "granite on which had been carved a potato bearing the carved word 'Aroostook.'"  .

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Specimen stone for Maine.
Closeup of Maine Rock Outline of Maine. Geo Map of Maine