spencer] MANGANESE DEPOSITS OF SANTIAGO, CUBA. 255 
has replaced in part, as was well seen upon the north side of the mine. 
The ores in these three mines occur about the summits and slopes of 
knolls which owe their elevation to the durability of the jasper against 
the processes of erosion. This jasper occurs in very irregular masses, 
between which the ore is found in equally irregular pockets, either 
pure, or, as has been stated, mixed with decomposed country rock. 
Frequently the ores are intimately veined or impregnated with streaks 
of jasper, when they become valueless, but as a rule the jasper occurs 
in well-defined nodules, which may be easily separated from the rock, 
which must be mined with the ore. 
The mode of occurrence in all of the localities mentioned is such 
that very large deposits can not be expected. A yield of 100,000 tons 
of first-grade ore from any one mine is estimated as all that can be 
expected in most cases, though if the attempt now being made to con- 
centrate the ores at the Boston mine is successful the marketable out- 
put will be greatly increased. 
The Ponupo mine has been worked on a large scale since the winter 
of 1898. It has standard-gage tracks laid to the ore chutes. A track 
has also recently been completed to the Boston mine, and can readily 
be connected with the Ysabellita. It is from these mines that the 
supply of Cuban manganese will be drawn for some time, though with 
the completion of the Cuba Central Railway a few other mines of 
importance may be developed. The amount of ore which ma}^ be 
anticipated from any one of them will not, however, warrant the 
construction of special tracks of any great length to bring their 
product to the trunk line. 
