After having duly considered the facts which are presented, I would not hesitate to offer, as an opinion, that the trap-rock formation was the original source of the masses of copper which have been observed in the country bordering on Lake Superior; and that, at the present day, examinations for the ores of copper could not be made in that country with hopes of success, except in the trap-rock itself; which rock is not certainly known to exist upon any place upon Lake Superior, other than Keweena Point.
If this opinion be a correct one, the cause of, failure of the mining company in this region is rendered plain. Having considered each insulated mass of pure metal as a true indication of the existence of a bed in the vicinity, operations were directed to wrong points; when, having failed to realize their anticipations, the project was abandoned without further actual investigation. We would be induced to infer that no attempts were made to learn the original source of the metal which was discovered, and thus, while the attention was drawn to insulated masses, the ores, ordinary in appearance, but more important in sitû, were neglected; and perhaps, from the close analogy in appearance to the rock with which they were associated, no distinction was observed.
What quantity of ore the trap-rock of Keweena Point may be capable of producing, can only be determined by minute and laborious examination. The indications which were presented by a hasty investigation are here embodied, and with deference submitted to your consideration.
I have the honor to be,
Sir, your obedient, servant,
DOUGLASS HOUGHTON.
Hon. Lewis Cass, Secretary of War.
2. Remarks on the Occurrence of Native Silver and Ores of Silver in the Stratification of the Basins of Lakes Huron and Superior. By Henry R. Schoolcraft.
Traces of this metal which have been found in the drift and boulder stratum of both Lakes Huron and Superior, indicate the existence of the metal in place. During my residence at St. Mary's, two specimens of its occurrence were brought to my notice. The first of these consisted of points of native silver in a moderately large mass of native copper, found in 1823, near the entrance of the Nama or Sturgeon River into Keweena Lake, of the large peninsula of that name, in Lake Superior. Like the majority of such masses of the region, it had no adhering portion of rock or vein stone, from which a judgment might be formed of its original position.
I had, the prior year, set up my mineralogical cabinet in my office, and stated to the Indians, who roved over large tracts, my solicitude to collect specimens of the mineral productions of the country of every description, and, indeed, of its zoology, always acknowledging their comity, in bringing me specimens in any department of natural history, by some small present; and I found this to be a means of extending my inquiries.
Subsequently, I received a boulder specimen from the shores of Lake Huron, containing veins of native silver. Part of the metal had been detached. I submitted these specimens to the Lyceum of Natural History at New York, in 1825. The following remarks are taken from their annals.
Mineralogical and Chemical Characters.—By examining this mineral, it will be perceived to possess the color, lustre, malleability, and other obvious characters of native silver. It is so soft as to be easily cut by the knife; and in a state of purity which permits it to spread under the hammer. These characters serve to distinguish it from antimonial silver, which is not malleable; from native antimony which tarnishes on exposure, &c. The metal occurs in thin, massive veins in the rock. These veins sometimes intersect, but never cross each other. It is also disseminated in small particles through the stone, or spread in flattened masses over its surface. Some of these masses were detached by the discoverer, but have been preserved, and are presented to the Lyceum with the more solid and undisturbed portions.