Copper - Pipe Amygdules
Cabinet, 9.9 x 4.7 x 4.7 cm
1st Level, Copper Falls Mine, Keweenaw County, Michigan
Ex. Skip Colflesh
I have never seen a copper quite like this in person, though they are referenced in pre-1970s finds here (see ROCKS & MINERALS vol 81 #4, page 266 for example). These copper crystals somehow extended during growth to fill spaces in amygdaloid deposits, and form these strange "pipes".