Fluorescent sodalite in Great Lake States

Perhaps you have heard of the latest collecting craze in the Upper Peninsula of Michigan?  Beach collectors who have generally restricted their collecting to agates, amygdaloidal basalt, and perhaps an occasional greenstone are now returning to the beach after dark with a long wave UV light source.  They are finding beach rocks that are bright yellow when subjected to a 365 nanometer long wave light source.  Apparently there are some beaches where these stones are relatively common.

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