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 birnessite with minor amounts of silicate minerals; one nsutite stream deposit has been identified. Crack deposit mineralogy resembles that of manganese dendrites. Cave and subglacial deposit mineralogy resembles that of manganese stream deposits. Although dendrites have long been considered to be pyrolusite, no example of pyrolusite mineralogy has been identified.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.