March-April 2009

Mineralogy and Paragenesis of Large Dolostone Septaria

In the Late Devonian Huron Shale, North-Central Ohio

by Ernest H. Carlson, Paul Schwin, Ksenija Namjesnik-Dejanovic

Large septarian concretions are abundant in the Huron Shale in a northerly-trending belt that extends from the Ohio River to Lake Erie (Carlson 1991, 2002). Excellent exposures are present along Scioto Brush Creek in Adams County, Paint Creek in Ross County, the Olentangy River in Franklin and Delaware counties, and the Huron River in Huron and Erie counties (Clifton 1957; Criss, Cooke, and Day 1988; Carlson 1991, 2002). This article describes the mineralogy of the Huron River portion of the belt, which is not well known (fig. 1). One of the authors (PS) has been collecting fine Huron River specimens for the past ten years.

Dr. Ernest H. Carlson is an associate professor of geology at Kent State University.
Paul Schwin is a horticulturist who has been collecting minerals for twenty years.
Dr. Ksenija Namjesnik-Dejanovic is a geochemist with an expertise in chemical analysis.

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