13 January 2011
Posted by Callan Bentley
Hopefully seasoned readers of this blog will remember this nice chunk of limestone with pyrolusite (MnO2) dendrites growing on its surface. I took some close-ups with my Nikon microscope a few weeks ago. Here they are; enjoy! The width of the field of view in each photograph is about 1.1 cm:
BTW, Mike likes dendrites, too.
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.
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I too thought that MnO dendrites were pyrolusite, but then I found this this paper:
Potter, R. and Rossman, G, 1979, Mineralogy of Manganese Dendrites and Coatings, American Mineralogist, v. 64, p. 1219-1226
A pdf can be found at this link:
http://www.minsocam.org/ammin/AM64/AM64_1219.pdf
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Your post highlights a nice specimen and photography.
Thanks for the link to my posting as well.