A Geoscience Digital Image Library

TitleDendrites of pyrolusite in moss agate from Montana
DescriptionThis is a polished slab of rock showing pyrolusite (MnO2) dendrites (the black “branching” or tree like deposit) in chalcedony (a microcrystalline variety of quartz, SiO2). The name “moss agate” is given to translucent chalcedony with dendritic inclusion of manganese or iron oxides.
LocationUSA ▹ Montana
PhotographerShannon Heinle. 2001-02-09.
CollectionUniversity of North Dakota Mineralogy Collection.
Key wordsmoss agate, pyrolusite, dendrite, chalcedony, Montana
Tech details963 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens.
GeoDIL number41