Autunite from Guilford, CT
Autunite {Ca(UO2)2(PO4)2 · 10-12(H2O)} on a non-fluorescing piece of typical New England pegmatite, complete with large plates of mica. This screamer is reportedly from a one-time find in someone's back yard in the Guilford area of Connecticut.  Thanks to Jared Woodward for this specimen.. If you are the guy whose backyard this came from, congratulations on a nice find.

Autunite is one of the few minerals that is both fluorescent and radioactive.  This is because the uranyl ion happens to be a fluorescent activator, a property which has nothing to do with the instability of the uranium nucleus.  Fluorescence (i.e., photon-mediated electron excitation and subsequent photon re-emission) has to do with the electron configuration of a given  atom,  molecule, or crystal structure.  Fluorescence is not a function of whether a nucleus is stable or unstable.

Specimen is quite large, I think about a foot across. There is no ruler handy, so I'll have to check later.


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