D. H. Browne — Phosphorus in Iron Mtn., Mich. 305 



sent up and dumped upon the Bessemer stock pile. Analysis 

 of this ore showed it to be from 'Oil to *027 phos. which will 

 be seen to agree with other analyses along this isochemic line. 

 (Kg. 21.) 



Below this 7th Level the intrusion of rock seems to have 

 caused an inflow of non-Bessemer ore. It appears as if the 

 rock had formed in shoal water on its lower side, and into this 

 shallow the calcium phosphate had drifted. I have noticed in 

 a large number of instances this tendency of rock occurring 

 as vein matter to alter the percentage of phosphorus in the 

 adjoining ore. In fact I do not know of any case wherein a 

 horse of jasper did not in some way alter the proportion of 

 phosphorus in the ore penetrated thereby. The statement that 

 high phosphorus follows rock is one which will be corroborated 

 by any one familiar with the mine under consideration. 



Another fact I must state is this : On the upper levels of No. 

 5 shaft almost all the ore was exceedingly high in phosphorus. 

 The ore found on the lower levels shows a greater uniformity, 

 the difference between Bessemer and non-Bessemer ore being 

 less evident than on the upper levels. It was no uncommon 

 occurrence on the third and fourth levels to find streaks of ore 

 as high as *350 phosphorus. Now such ore is very rarely met 

 with. The average of non-Bessemer ore in the west end of 

 the open pit and the upper levels of No. 5 shaft was some- 

 where near *150 phosphorus. The averages of non-Bessemer 

 at present obtained is probably "075 or "080. Again, on 'the 

 upper levels the greater part of the ore near No. 5 shaft was 

 non-Bessemer ; at present the converse is the case, the first-class 

 ore occupying the greater portion of the deposit. To state in 

 general terms, the tendency of the phosphorus on this vein 

 seems to be to increase with the distance from the lower point 

 of the deposit. This is not true of the eastern end of the de- 

 posit, at No. 1 shaft, in which the upper levels are largely 

 Bessemer ore. This seems due to the fact that a horse of rock 

 splitting up the deposit has thrown the current of Bessemer 

 ore to the east. This Bessemer ore, occurring on the upper 

 levels of No. 1, is of the same content in phosphorus as that 

 on the 5th and 6th levels of No. 5 Shaft, and the high phos- 

 phorus ore on the lower levels of No. 1 is the same as that now 

 being met with on the 7th and 8th levels of No. 5 shaft. 

 Fig. 23. 



In endeavoring to correlate these isochemic lines with the 

 physical phenomena of the deposit, the only theory which will, 

 to my mind, furnish adequate explanation, is that of aqueous 

 deposition. The easy longitudinal cleavage of the laminae of 

 ore, the curvature in small veins of the hanging wall toward 

 the footwall, and the hydrated muddy look of the ore next 



