446 



MAGNETIC IRON-BEDS 



than fifty feet of quartz and iron, in about equal proportions. In the wild and deep 

 ravines where the Bad River breaks through the range, there is a cliff of slaty ore, 

 most of which comes out in thin, oblique prisms, with well-defined angles and 

 straight edges, probably three hundred feet thick, including what is covered by the 

 talus or fallen portions. I estimate more than one-half of this face to be ore ; and, 

 in places, the beds are from ten to twelve feet in thickness, with very little inter- 

 mixture of quartz. There are portions of it not slaty, but thick-bedded. The dip 

 of the laminae is mostly north and by east, 80° and 85°. The convulsions that 

 have occurred at this point have thrown a part of the range beyond the rest of it, 

 to the northward, so that in crossing the river, and passing along the mountain to 

 the eastward, for several miles, the ferruginous bed, as well as many of the associate 

 strata, were not visible above the general surface of the ground. It should, however, 

 be borne in mind, that the whole region is not only covered so thickly with timber 

 that no distant views can be had without climbing trees, but the drift often con- 

 ceals the rocks, over a large proportion even of the elevated ridges ; in addition, 

 the rocks themselves, previous to the era of the drift, have been the sport of giant 

 forces, which tossed and tilted them about at various angles and elevations, realizing 

 the fable of Atlas. 



Where the west branch of Tyler's Fork crosses the chain, Mr. Beesly found the 

 southerly face of the uplifts well charged with a rich, heavy ore, showing thirty, 

 fifty, and seventy feet, with iron predominating over quartz. 



All the specimens we saw were of the black magnetic oxide, without any of the 

 red. The surface was not affected by weather, the angles of the rectangular slaty 

 pieces and blocks that have fallen from the cliffs in great numbers, were entire, 

 and not rounded by time. I infer that the mineral contains in its composition a 

 notable proportion of silex. 



The productive yield of such an ore can only be determined by trial in properly 

 constructed furnaces, but judging of our specimens by weight, they will afford 

 fifty to sixty per cent, of metal. The analysis of one specimen (No. 7) by Dr. 

 Owen, yielded over sixty-six per cent.* For present use a supply of ore may be 

 obtained from the rubbish at the foot of the uplifts, in blocks and pieces already 



* The analysis of Specimen No. 7, from the slaty beds of the mountain, south of Lac des Anglais, gave 

 as follows : 



Peroxide, . . . . . . .51-5 



Protoxide, . . . . . . . 27 - 1 



Mixed oxides of iron, ..... 78-6 = 56-3 iron. 



Silica, ........ 20-8 



Magnesia, . . . . . . . 00-6 



Alkali, ....... 00-2 



Fluoric acid, ....... a trace. 



100-2 



The excess arises from an absorption of oxygen by the protoxide. The analysis is subject to revision, 

 if time permits, in this particular, but the result in pure iron cannot be materially changed. This speci- 

 men is apparently 10 or 20 per cent, below the richest pieces brought from the Range, and is above some 

 of the poorer slaty specimens, 



