SOME PRINCIPLES CONTROLLING THE DEPOSITION 



OF ORES. 1 



I would hardly have ventured to talk on the subject of ore 

 deposits to you if I had not approached the subject from a differ- 

 ent point of view from the majority of men who have consid- 

 ered it. The point of view from which the subject of ore 

 deposits has been most frequently considered has been that of a 

 study of ore deposits themselves. A geologist or mining engi- 

 neer has studied this or that ore deposit, or a number of ore 

 deposits in different districts, and has then generalized con- 

 cerning the ore deposits of other districts, and perhaps of the 

 world. I also have considered the subject of ore deposits to 

 some extent from that point of view, but if I had done this 

 only, I would not have ventured to give a general address upon 

 the subject. 



Some years ago I took up the question of the alterations of 

 rocks — the alterations of all rocks by all processes. In treating 

 this subject it became necessarj' for me to consider somewhat 

 fully underground water ; the principles which control its flow ; 

 the manner in which it works ; the results which it accom- 

 plishes. After I had reached certain conclusions upon that 

 subject it seemed to me that the deposition of most ores was a 

 special case falling under the general principles controlling the 

 work of underground water. Therefore it is from the point of 

 view of the circulation and work of underground water that I wish 

 to consider the subject of ore deposits tonight. However, I can- 

 not go into the subject fully, and will be obliged to ask those of 

 you who are especially interested in it to refer to my more 



1 An address presented to the Western Society of Engineers at Chicago, June 13, 

 1900. The address is also printed in the journal of that society for December 1900. 



This paper covers the same ground as a paper on the same subject, in a some- 

 what different form, which has already been published in the Transactions of the 

 American Institute of Mining Engineers. Vol. XXX, 1900, pp. 1— 151. 



730 



