162 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
exist it seems fair to anticipate, but the best method for their diseov- 1 
ery must be based upon a recognition of their character as distinct 
from the primary ores. 
Secondary ores will not be found where the inclosing rocks are tight | 
and impervious to the circulation of atmospheric waters. They requ ire t 
loose formations due to brecciation or crushing of the country rock, as ; 
in the cases mentioned, and in some cases it is to be expected that 
the country rock will be greatly decomposed. Several locations were ! I 
noted by the writer where gossan was present in encouraging amount, ! { 
but where no adequate work had been done to prove the condition of, 
the inclosing country rock or the significance of the gossan. Other! 
properties show the presence of rich sulphides in crushed and decom-fl 
posed diorite, and it is believed that these are worthy of careful 
investigation. 
