A very unusual specimen from the Michigan copper country.  To begin with, the White Pine Mine is best known for rather flattened copper growths-- the mine worked the Nonesuch Shale beds, laminated strata lacking the open space that allowed for the more three dimensional growth seen in specimens from other northern Michigan mines, which worked through basalt flows.  Considering that lack of growth space, it is somewhat unusual to find such a well formed calcite crystal from the location.  Even more unusual is the silver/ calcite association-- copper/ calcite specimens are known (particularly from the Quincy Mine) but to have a silver/ calcite from anywhere in the region is quite unusual.  A cool rock for the collector of Michigan or Midwestern minerals.