Pegmatite from Midcontinent Rift, USA
USA | |
| (2005) Mineral Resources Data System (MRDS), US Geological Survey. |
| Bornhorst T. J., Rose W. I., (1994) Self-guided geological field trip to the Keweenaw Peninsula, Michigan. |
| (2005) Mineral Resources Data System (MRDS), US Geological Survey. |
| (2005) Mineral Resources Data System (MRDS), US Geological Survey. |
Clark Mine, Copper Harbor, Grant Township, Keweenaw County, Michigan, USA