With the exception of the referred to by Dablon which was possibly a piece of mass copper projecting out of the water at a shallow spot near the shore, all of the copper found as late even as the latter half of the 18th century appears to have been afloat,' that is, masses of smaller or larger size that had been transported from their original beds, generally by glacial action. Indeed it was this fact that probably explains the statement of Capt. Jonathan Carver in 1778 that the copper itself costs nothing.
The area of "float" copper appears to have extended much beyond the territory immediately tributary to Lake Superior, for in 1700 Le Sueur found pieces of it near the mouth of the Chippewa River and another about four leagues above the mouth of the Saint Croix River, in Wisconsin. In later years similar finds have been reported as far south as Indiana and Illi nois. But while Lake Superior was supposed to be the source of this copper we do not find any evidence that any white man — except always Father Hennepin — had even seen anything that could be called a copper mine (sic), as early as the time of Charlevoix. The latter in his his tory of New France, published in 1744, says "It is certain that there has been discovered in sev eral places a considerable quantity of this metal, without even being obliged to dig much." It is true that La Hontan early in the 18th cen tury speaks of copper mines on Lake Superior, but he does not claim, like Hennepin, to have seen them. We also find many references to copper "mines" in the interior as reported by the Indians, who usually showed great reluc tance to disclose their whereabouts to the white man.
Thus far the pieces of native copper fotmd on Lake Superior were gathered on the edges of the islands and on the borders of the lake along the highways of navigation by canoe. It was not until 1765 that Alexander Henry, at tracted by Indian reports of a large mass of copper, the one referred to by Dablon, visited the Ontonagon River and went up stream several miles above the junction of the east and west branches. He found, on a clay bank, at or near the edge of the stream, the copper mass, with some rock adhering to it through whic.h ran small veins of copper. In 1771, revisiting the same place, he noticed also much copper bedded in stone, and left a party of miners there, "to make a trial on the hill, till we were better able to go to work on the solid rock."
They dug 40 feet into the clay bank and found frequent masses of copper. All went well dur ing the winter, but when spring came, the clay thawed and caved in, and the party left. In re cording the above facts, Henry added that "The copper ores of Lake Superior can never be prof itably soug'ht for but for local consumption. The country must be cultivated, and peopled, before they can deserve notice." In a footnote to the above, having in mind the more roseate view then recently expressed by Alexander Mackenzie and earlier by Captain Carver, he adds, "The copper mines of Lake Superior have been more than once represented to the world in colors capable of deceiving fresh adventur ers: and the statement in the text will not have been uselessly made, if it should at any time serve as a beacon to the unwary.) The fame of Henry's operations was probably spread abroad at the time, although his book was not published until 1809.
Henry's visit to the Ontonagon River marks the culmination of the efforts of two and a half centuries of search for the original source of the I.ake Superior native copper —its location in the rocks of volcanic origin that almost sur round that inland sea. It also marks the begin ning of an industry that in spite of Henry's warning has grown to be one of the most im portant of the Northwest. Possibly the troubles that distracted the country during two wars, and die boundary disputes in the region of the Great LaIces, rather than the adverse sentiment caused by Alexander Henry's failure, kept back the de velopment of the capper district of Michigan, but the spirit of exp.ansion which during the administration of Jefferson found expression in the expeditions of Lewis and Clark and of Pike later found an echo in Gov. Lewis Cass, at whose Initiative and under whose personal lead ership an expedition to the Northwest was effected in 1820, one of the objects of which was to investigate the copper "mines" of LaIce Su perior. Henry R Schookraft accompanied this expedition as mineralogist. They visited the Ontonagon copper mass, which Schoolcraft recognized as having been removed from its original bed of "serpentine" rock; from which circumstance he inferred that there must be ex tensive "mines" in the vicinity.