96 RURAL MICHIGAN 



Percentafje of Content. 



Marquette Range: Iron, 54; phosphorus, .03; silica, 8 

 mantrancse, .24; moisture, 8. 



Menominee Range: Iron, 53; phosphorus, .04; silica, 8 

 manganese, .18; moisture, 7. 



Gogehio Range: Iron, 53; phosphorus, .04; silica, 7 

 manganese, .39; moisture, 11. 



At the beginning of mining operations, masses of 

 ore were often found about the surface of the ground, 

 the result of glacial action, and in outcrops, occa- 

 sionally in the form of "iron mountains." The first 

 mining consisted, then, in removing this most ac- 

 cessible portion of the visible ores. Later, open pits 

 were frequently sunk, such mines still obtaining at 

 a few points, as near Wakefield. Such exploitation 

 of the ore bodies liad the character of quarrying, 

 which in time was extended beneath the surface of 

 the ground; and eventually true shafts of consider- 

 able depth were driven along the veins, involving 

 extensive surface construction of hoists and other 

  equipment. While there is some "bog ore" in the 

 Upper Peninsula, as in the Seney swamp, this is of 

 no commercial importance. The question is often 

 asked as to how long the iron ore and copper de- 

 posits in the Lake Superior region will continue to 

 be workable. In 1921, the State Geologist reported 

 a visible supply of iron ore in Michigan of two hun- 

 dred million tons, with an annual production from 

 twelve to eighteen million tons. It is evident that 

 the industry has a definite period of duration not 

 very prolonged. There remains the possibility of 

 utilizing low grade ores, not at present being worked, 



