Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 / Resumed and Completed, by the Discovery of its Origin in Itasca Lake, in 1832

by Henry Rowe Schoolcraft

CLASS III. Combustibles.

33. Peat. Marine sand formation composing the shore of Lake Superior, between White-fish Point and Grand Marais. Also, on the island of Michilimackinac.

CLASS IV. Ores and Metals.

34. Native copper. West side of Keweena Point, Lake Superior. Imbedded in a vein with carbonate of copper, and copper black, in the trap-rock.

35. Copper black. With the preceding.

36. Carbonate of copper, green. With the preceding.

These two minerals (35 and 36) characterize the trap-rock of the peninsula of Keweena, Lake Superior, from Montreal Bay, extending to and around its extremity, west, to Sand-hill Bay. The entire area may be estimated to comprise a rocky, serrated coast of about seventy-five miles in length, and not to exceed seven or eight miles in width. The principal veins are at a point called Roche Verd, and along the coast which we refer to as the Black Rocks. At the latter, native copper is one of the constituents of the vein.

Green and blue carbonate of copper was also observed in limited quantity, in small rounded masses, at one of the lead diggings near Mineral Point, Iowa County.

37. Chromate of iron. Presque Isle, Lake Superior.

38. Sulphuret of lead. Lead mines of Iowa County, Michigan Territory.