Sufficient attention does not appear to have been bestowed, by mineralogists, upon the metalliferous soil of the Mississippi Valley. It is certainly very remarkable that such vast deposits of lead ore, accompanied by veins of sulphate of barytes, calc spar, and other crystallized bodies, should be found in alluvial beds; and it would be very interesting to ascertain whether any analogous formations exist in Europe, or in any other part of the earth's surface. It is one of the most striking features of this deposit, that the ore, spars, &c., do not appear as the debris of older formations, and have no marks of having been worn or abraded, like those extraneous masses of rock which are very common in the alluvial soil of our continent. The lead ore and accompanying minerals appear to have been crystallized in the situations where they are now found. We should, perhaps, except from this remark the species of lead called _gravel ore_ by the miners, which is in rounded lumps, and is never accompanied by spars. Sulphuret of lead is also found near the spot where the small River Sissinaway enters the Mississippi, and two leagues south of it, upon the banks of the River Aux Fevre, at both of which places considerable quantities have been raised, and continue to be raised, for the purposes of smelting, by the Fox and Sac tribes of Indians. At these places, it is most frequently connected with a gangue of heavy spar and calcareous spar, with pyrites of iron. I procured from a trader, at Dubuque, several masses of galena crystallized in cubes and octahedrons. In descending the Upper Mississippi, a specimen of galena was exhibited to me, by a Sioux Indian, at the village of the Red Wing, six miles above Lake Pepin, said to have been procured in that vicinity. Galena is also reported to have been discovered in several places on the south side of the Wisconsin River, and these localities may be entitled to future notice, as furnishing important hints. 3. ZINC. The sulphuret of zinc (black blende) is found disseminated in limestone rock along the banks of Fox River, between the post of Green Bay and Winnebago Lake. Although frequently seen in small masses, no body of it is known to exist. I also found blende, in small, orbicular masses of calcareous marl, along the east shore of Lake Michigan, between the Rivers St. Joseph and Kikalemazo. 4. IRON. This mineral is distributed, in several of its forms, throughout the region visited, although but little attention has yet been directed to its exploration. In the basin of Lake Superior it exists, in valuable masses, in the form of a magnetic oxide, on the coasts of the lake between Gitchi Sebing (Great River), called by the French Chocolate River, and Granite Point. Specimens from Dead River (Riviere du Morts) and Carp River, the Namabin of the Indians, in this district, denote the latter to be the chief locality. It is the iron glance, and occurs in mountain masses.