A handwritten provenance report for this piece notes that it was originally part of the collection of Captain John Daniell, who "opened the Tamarack Mine in 1882" (https://en.wikipedia.org/wiki/Tamarack_mine). The collection was sold to Wards in ca. 1950, who sold it that year to Robert Hesse (Glenside PA). Thence to Dick Hauk, Ed David, Phil Scalisi (by trade), who sold it to Eric Asselborn ca. 1996. Rob Lavinski purchased it as part of the Asselborn collection, and sold it to Mark Pospisil in 2016. In addition to this strong and credible provenance, the piece is of itself a fabulous example of Michigan coper-in-calcite, so much so that the author of the provenance report noted that Stan Dyl II ( former Seaman Museum director, who in 1991 published "The Michigan Copper Country" special issue of the Mineralogical Record, with co-author Marc L. Wilson) "has been excited about the specimen for years, even though he had never seen it".
Calcite with Copper Inclusions
Tamarack Mine, Calumet Township, Houghton County, Keweenaw Peninsula, Michigan, USA
Inventory # 02282