Tenorite - (Donated)
Large Cabinet, 26.3 x 23.9 x 6.0 cm
Copper Harbor, Keweenaw County, Michigan, USA
Ex. Philadelphia Academy of Natural Sciences
A massive, basketball-sized hemisphere of heavy metallic Michigan minralization...I have not ever seen quite the like of it before. Courtesy of Dr. George Robinson at the Seaman Museum: The specimen appears to be tenorite, probably from Copper Harbor, Keweenaw County (melaconite is an old name for tenorite). The only other possibility would be from the Algomah mine in Ontonagon Co., but the Copper Harbor material was found as glacial float and is typically rounded over like the piece you describe here. Both locations have minor chrysocolla and malachite associated. The "with paramelaconite?" on the label, however, is a little confusing, since that was known only from the Algomah mine, but as small black pseudomorphic crystals on fracture surfaces of angular rock matrices rendered so from the mining process.We have smaller pieces from each occurrence in the collection, but nothing as large as the one in your picture!. Well, they do now...proudly donated to the Seaman Museum.