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.
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
Your post highlights a nice specimen and photography.
Thanks for the link to my posting as well.