474 



NA TURE 



[March 17, 1898 



efficiency of the niininf; and'' metallurgical plant in use. Un- 

 doubtedly llie p;reatest advantage possessed by the United States 

 is that in the Lake Superior region they have the most extensive 

 supplies of cheap and rich iron ores known to exist. It is to 

 the sudden development and unparalleled richness of tliese 

 deposits that the United States chiefly owe their cheap pig iron. 

 It is, therefore, a matter of extreme satisfaction that an authori- 

 tative description of these deposits has been prepared by Mr. 

 Horace \' . Winchell for English readers in the form of an 

 admirably illustrated monograph,^ covering seventy pages of the 

 Transactions of the Federated Institution of Mining Engineers, 

 and dealing with the history, geography, geology, and mining 

 industry of the iron-ore region. Only forty years have elapsed 

 since the first regular mining of iron ore was begun in the dis- 



The iron-ore belts or ranges are situated chiefly in the Stales of 

 Michigan and Minnesota. The beds occur in rocks of pre- 

 Silurian, and probably of preCambrian age, the determination 

 of the geological age resting wholly on structural evidence. As 

 to the genesis of the ores, there has been much speculation. 



Oliver Iron Mine, showing a face of ore 50 feet high. 



trict, and during that time up to January x, 1897, the total out- 

 put was as follows : — 



Range. 

 Marquette 

 Menominee 

 Gogebic 

 Vermilion 

 Mesabi 

 Miscellaneous 



First year. 

 1856 

 1880 

 1884 

 1884 

 1892 



Total production to date 



Tons. 



46,538,187 



22,994,428 



20,788,787 



9,220,235 



8,074,583 



2,320 



107,618,540 



According to the official statistics, the production in 1896 was 

 as follows : — 



1 " The Lake Superior Iron-ore Region." By Horace V. Winchell. 

 (Excerpt from the Transactions of the Federated Institution of Mining 

 Engineers, 1897.) 



NO. 1481. VOL. 57] 



The principal theories are ( i ) the obsolete one that the ores are 

 of eruptive origin ; (2) that they are mechanical sediments ; and 

 (3) that they are of chemical origin. Under the third head, the 

 chemical action may have been that of original precipitation, or 

 that of replacement or segregation of chemical or clastic materials 

 by the substitution of iron oxides. Mr. Winchell inclines to the 

 theory of oceanic precipitation advanced by him in 1889. He 

 considers, however, that there is no reason to suppose that all 

 the iron-ore deposits were formed in the same way. 



From an engineering point of view, the Lake Superior region 

 is remarkable for the manner in which labour-saving appliances 

 are adopted for extracting the iron ore and for loading it into 

 railway waggons and vessels. The result being that at the 

 present time the mining cost is much below that at any previous 

 period. Thus in 1890, when the Iron and Steel Institute visited 

 the Lake Superior iron mines, the average cost of mining was 

 ^s. per ton. At the present time it is is. 6d. per ton. In most 

 cases the methods of mining adopted are those usual in under- 



