MARION COUNTY. 101 



twenty specimens analyzed six showed only traces of phosphorous, while the 

 others contained that metal in proportions varying from sixteen-hundredths 

 to three hundredths of one per cent. While the sulphur in the same number 

 of analyses shows traces only in five of the specimens, throughout the others 

 the percentage ranges from thirty-seven-hundredths to seven-hundredths. 



In silica the Marion County ores rank low. In the twenty analyses made 

 in the laboratory of the Survey, only five rank above seven per cent. Eight 

 have percentages lower than five per cent, and of these eight five do not ex- 

 ceed two per cent. Of the ores exceeding eight per cent of this impurity, 

 Nos. 32, 36, and 332 have the high percentage of 



No. 32 '. 27 . 33 per cent. 



No. 36 26.435 percent 



No. 332 22 . 54 per cent. 



Three of the ores show the presence of manganese. These are 



No. 26, showing 0.1264 per cent of manganese. 



No. 29, showing 0.14*7 per cent of manganese. 



No. 36, showing 1.895 per cent of manganese. 



None of these ores show any traces of chromium or titanium. 



In magnesia and lime only two, Nos. 29 and 36, show any appreciable 



quantity of magnesia. 



No. 29 shows . . 0.235 per cent of magnesia. 



No. 36 shows 1.014 per cent of magnesia. 



And Nos. 15, 16, 17, 26, 34, 35, 316, 318, and 320 show traces only. In 

 lime the percentages are also low, and in no analysis made shows over 1.57 

 per cent. 



The most extensive deposits of iron ore found in Marion County are, first, 

 a deposit lying in the western part of the county close to the lines of Morris 

 and Cass counties. This field, which may be designated the Western Iron 

 Field, covers the lands embraced by the John H. Johnson, McKinney, and 

 Williams (two head rights), a triangular area in the northern portion of the 

 Walter H. Gilbert, the whole of the James Graham with the exception of a 

 small portion of the southeast corner, the southeast quarter of the James 

 Alley, and the International and Great Northern Railroad Company's head- 

 rights, comprising an area of about four square miles. This bed is but the 

 southern end of the extensive deposits of iron ore bearing material and iron 

 ore which extend into, and have their greatest development in, the south- 

 western portion of Cass County and along the southeastern border of Morris 

 County. 



The ore of this field is mostly limonite of the geode, or nodular concretion- 

 ary, variety, with some laminated ore, with a deposit of conglomerate ore 

 forming a fringe around the lower elevations and along the courses of the 

 streams. 



