294 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 



declining output are manifest in the case of the Vermilion. The 

 vast increase in the output of iron ore is due to the Mesabi Range, 

 and from it in 1912 came nearly 60 per cent of the country's total. 

 A marked decline in available supply from the Mesabi would bring 

 about a greater falling off in ore supply than any possible increase 

 in the other Lake Superior ranges, or than the present sources of 

 supply from other mining districts, could make good. The Mesabi 

 Range is the key to the maintenance of the domestic supply at its 

 present grade, and when it declines we must appeal to foreign sources 

 to keep the iron and steel industry in its present position. 



YIELD OF THE ORES. 



Conditions vary greatly in different parts of the country; at 

 different times; with different ores; and with the entrance of new 

 sources of supply. It is a general truth that the richest ores are 

 obtained in the early days of mining, As time passes and the in- 

 dustry becomes firmly established, lower and lower grades come 

 within the range of profit. Alabama Clinton ores gave much higher 

 percentages when mined wholly above the permanent water level 

 than they do now, when pursued below it. For many decades only 

 lump ore, and much of that over 60 per cent iron, was produced 

 by the magnetite mines of the eastern Adirondacks. To-day the 

 greater portion of the ore goes first through a magnetic concentrator 

 before it is shipped. In earliest years on Lake Superior hard, 

 specular ore at 65 and above was sought. With improved facilities 

 the grade came down to and below 60, but the soft ores found slight 

 sale. Now the soft, earthy ores are the principal objects of mining, 

 and the average grade is well down in the fifties. Important ship- 

 ments of ore with percentages below 50 have been placed on the 

 steamships. 



In the summer of 1875, Prof. Albert H. Chester,^ an experienced 

 chemist, ^dsited the Lake Superior region in the endeavor to secure 

 average samples from the stock piles of the larger mines, all, of 

 course, at that time in the Marquette range and shipping hard, specu- 

 lar ores. Four samples ranged from 61.01 to 66.83 and probably give 

 a fair idea of the ore at that time sent away. Iron Mountain, Mo., 

 ore ran 64.87; Lake Champlain magnetites, 56.01 to 62.68; Clinton, 

 N. Y., fossil ore, 44.57, but yielded 43 in the furnace. 



In September, 1890, Geo. W. Goetz^ published a tabulated series 

 of analyses from the four older Lake Superior ranges, which, when 

 averaged, afford the following values. To give a correct average, 

 the analysis of each mine's ore ought to be weighted with the output, 

 and as the data for this calculation are not available, we must be 



1 Albert H. Chester, " On the Percentage of Iron in Certain Ores." Trans. Amer. Inst. 

 Min. Eng., vol. 4, 219, 1875. 



^ Geo. W. Goetz, "Analyses of Lake Superior Iron Ores," Idem, vol. 19, 59, 1890. 



