Ex. University of Michigan Geology Department, Specimen #UM2272
Dark colored Biotite Mica crystals attached to a dark colored matrix of unidentified composition. The Biotite crystals appear black on the flat surfaces and dark brown on the edges and are likely Fluorophlogopite. There is a small amount of Willemite in the matrix which fluoresces bright green under SW UV. The labels were wrapped in the page from a day calendar from 1951 but appear to be much older.
Condition: Composed of massive material.
Flaws: Nothing Appreciable
This mineral is also found in the following galleries: Minerals From New York, New Jersey and New England | Phyllosilicates | Minerals Priced Between 25 and 49 Dollars