An IMPRESSIVE and DRAMATIC CABINET copper "skull" from the Red Jacket Shaft of the Calumet and Hecla Mine, near Calumet, Michigan. This is a very 3-dimensional cast, with the copper forming around conglomerate cobbles. The cobbles were dissolved away and further tectonic activity caused the back of the cast or "skull" to bend inward, dividing the bottom of the cast and looking like a sail. Highly unusual.