Location of the Cardiff Green Marble Company that mined serpentinite that was used as a decorative stone in many buildings, including the Empire State Building in New York City.  This shaft measures about 90 feet square and is over 300-feet deep.  Presently, the shaft is water-filled to a depth of about 40 feet.  The serpentinite was mined from the 1920’s until the mid 1980’s