|Native Copper, Caledonia Mine. |
This is a heavy lump of naturally occurring copper from the Caledonia Mine, Ontonagon County, Michigan. Like several of the dozen samples I got from the same source, this one has what look like impressions of pebbles, as it was compressed around them at some point in its history.
Source: Larry Curtis
Contributor: Theodore Gray
Acquired: 10 June, 2003