Ferromanganese Deposits in the Saranac Lake System New York

Abstract

In situ observations of ferromanganese deposits have been made in the Saranac lake system, New York. The ferromanganese occurs on shallow, sandy bottoms as rims and coatings on cobbles and exposed bedrock. The deposits have a rather high Fe: Mn ratio, averaging 4, and are otherwise chemically similar to freshwater ferromanganese reported in the literature. In cross-section, the rims exhibit a layered structure resulting from alternating periods of high and low Mn deposition at the leading edge of the rims, presumably in response to changing physical or biological conditions in the environment.