This is one of my favorite pieces in the update-- a highly unusual combination of a MATRIX datolite with copper. Michigan's Upper Peninsula is primarily known for 3 species: copper, silver, and datolite. The first two frequently occur together, but apart from tiny metal inclusions, datolite is almost always found alone, as loose nodules.
This piece has a half-polished datolite nodule that is attached to a bit of matrix, which is composed of a mixture of copper and stone. There is also a copper crystal on the matrix next to the datolite. I've only ever seen a couple matrix examples of these UP datolites-- this piece is actually quite special.