128  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
and  others  would  precipitate  the  metal  from  dilute  solutions.     The  solutions,  moving  down 
the  dip  in  the  various  sandy  beds,  would  rise  when  they  reached  the  fissure  and  an  artesian 
circulation  would  be  established.     In  the  fissure  the  mingling  of  solutions  would  cause  a] 
precipitation  of  metallic  sulphides.     The  absorptive  action  of  the  kaolin,  which  is  abundant 
in  the  zone  of  crushed  quartz,  may  also  haveoperated  to  deposit  the  ore. 
The  veinlets  of  argentiferous  copper  sulphides  suggest  that  there  has  b^en  a  secondary 
concentration  of  the  ore.  All  the  metallic  minerals  belong  either  to  the  group  which  is 
commonly  regarded  as  secondary  or  are  those  which  usually  occur  in  the  oxidized  zone.  So 
far  as  the  development  has  proceeded,  there  is  nothing  to  indicate  that  the  original  ore  was 
a  copper-iron  sulphide,  for  pyrite  and  chalcopyrite  are  almost  entirely  absent,  and  a  com- 
plete analysis  of  the  dump  gave  less  than  2  per  cent  of  iron. 
