Ruck's Pit is
an aggregate quarry near Fort Drum, Florida. During digging operations, an abundance of well-fossilized and calcified marine shells in the sandy fossiliferous limestone of the Pleistocene-age Nashua Formation was discovered. The cavities within fossil clam and whelk often contain honey-colored calcite crystals up to about 1" in length. Fossilized bone and teeth, although rare, can also be found at this location.
The Southeast Federation of Mineralogical Societies' Dixie Mineral Council sponsored a field trip to Ruck's pit that was hosted by the Jacksonville Gem and Mineral Society. Having seen many fine specimens from this location, on Saturday, January 18, 2003, Chrissy and I decided to make the LONG drive to Fort Drum from hour home in western North Carolina.
Those who wanted to hunt calcified shells had two options: 1) Collect loose specimens on a large rock pile or 2) Work the hard limestone walls to retrieve loose specimens and those in matrix.
Chrissy at Rock Pile
Chrissy and I started out the day working a relatively soft sandy limestone wall that contained mostly calcified whelk fossils with a few fossil gastropods.
The interior chambers of these fossils are covered with tiny honey-colored calcite dog-tooth crystals. After breaking too many specimens into pieces in the field by trying to split them open with hammer and chisel, we decided that it would be better to cut them open with a rock saw at home. Only about a third of the fossils contained calcite interiors, but taking home a bunch of clinkers was an easy price to pay for all the good ones.
Cut but still closed
Cut Fossil
Close-up
Cut and partially open
CutFossil
Close-up
Another area of the mine where we spent part of the afternoon produced mostly calcified clam shells. The very hard fossiliferous limestone was below the groundwater table, but, lucky for us, the mine is de-watered with large pumps to allow access to a location that would otherwise be beneath many feet of water.
Collecting in this area was wet and muddy, but very worthwhile.
It was a long haul back and forth from south Florida, but we're tickled to have made the trip!
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