Pennsylvania Blue Marble

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01neighborhood_rect540Bizarre marine arthropods of the Cambrian Explosion roamed a vast sea which covered what is now Valley Forge National Park.  Relax, we refer to events of 450 million years ago.  Under this sea there formed a weakly metamorphosed calcite marble.  FaDSCF0182st forward, to the early days of The Republic.  This Pennsylvania Blue Marble became an  important regional building stone in the first half of the nineteenth century.

One has but to tour older Philadelphia row home neighborhoods to see its extensive use as steps,  window sills, lentils, and trim.  Alas, structural decomposition, changing design tastes, and improved transportation systems increased  availability of better quality white marbles from New England and Georgia.   What becomes of the Pennsylvania marble as buildings are pulled down?

People like me collected steps and sills in nicer condition for garden use.  Wear patterns tell the story of healthy, prosperous neighborhoods.  Tool marks upon the ends aidScreen Shot 2014-06-01 at 9.58.35 AM one in establishing production date, as methods of stone dressing evolved.  The 350 pound steps were welcomed by friends and neighbors, as well.  A unique pillar for the garden bird bath or flower-pot.  And the sills make great bordering stones!  Pictured is a local effort.  These stones were pulled from houses under demolition within Philadelphia’s Fairmount section.

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2 thoughts on “Pennsylvania Blue Marble

    Anasazi Stone Co • Scottsdale AZ « American Toolbox said:
    January 18, 2015 at 7:17 am

    […] with bedded sedimentary rocks with fissile bedding planes. Examples include Arizona flagstone and Pennsylvania Bluestone. – Anasazi […]

    American Toolbox responded:
    July 2, 2015 at 9:14 am

    The “Pennsylvania Blue Marble” link within the article is no more. University of Pennsylvania changed their web address.

    A google search reveals many interesting articles: https://www.google.com/search?client=safari&rls=en&q=pennsylvania+blue+marble&ie=UTF-8&oe=UTF-8

    Here’s one I particularly liked. – editor
    http://www.chipstone.org/html/publications/2002AF/Chinnici/2002ChinniciIndex.html

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