Mineralogy of manganese dendrites and coatings
Russel M. Potter and
George R. Rossman
Division of Geological and Planetary
Sciences
California Institute of Technoogy
Pasadena, CA 91125
Abstract
Infrared spectroscopic study of desert varnish, manganese dendrites,
river deposits, and other manganese oxide concentrations of the
terrestrial weathering environment has shown that the morphological
distinctions among them have a sound basis in differences in their
mineralogy. The manganese oxide in manganese dendrites collected in
surface exposures is either romanechite or a hollandite-group mineral.
These are mixed with varying amounts of silicate minerals, which are a
passive substrate for the oxide deposition. Dendrites collected in
underground mine workings are todorokite. Manganese stream deposits are
generally birnes site with minor amounts of silicate minerals; one
nsutite stream deposit has been identified. Crack deposit mineralogy
resembles that of manganese dendrites. Cave and subglacial de posit
mineralogy resembles that of manganese stream deposits. Although
dendrites have long been considered to be pyrolusite, no example of
pyrolusite
mineralogy has been identified.
last updated: 5-Oct-2020