About one mile west of Milan, Ohio, which is two miles south of Exit 7 on the Ohio Turnpike, the Huron River cuts through flat-lving beds of the marine Ohio and Olentangy shales of Upper Devonian age. Concretions one to three feet in diameter are quite common here and many are septarian. Three years ago Clarence Raver, an amateur rock hound from Clarksfield, Ohio, began breaking these open and collecting specimens of fluorescent calcite, dolomite, ankerite, barite, marcasite, quartz and sphalerite. He was unable to identify one colorless crystalline material, several pounds of which he found in more than 25 septarian concretions.

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