588  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.  [bull.  260. 
concentration  this  is  brought  up  to  44  or  45  per  cent.     An  average 
sample  of  mill  ore  would  give  about  the  following  analysis: 
Average  sample  of  mill  ore  from  Stella  pyrite  mine,  St.  Latvrence  County,  N.  Y. 
Sulphur    28 
Iron    29 
Silica 32 
Lime  and  manganese 1.5 
Zinc   .  3 
Copper    .2 
At  the  time  of  the  writer's  visit  the  mill  was  being  remodeled,  and 
New  Century  jigs  were  being  substituted  for  Hartz  jigs.  The  prac- 
tice had  been,  after  picking  out  ore  of  sufficiently  high  grade  to  be 
marketable  as  lump,  to  crush  the  remainder  to  1^  inch,  then  by 
rolls  to  one- fourth  inch.  The  material  from  the  rolls  was  passed 
through  two  sets  of  screens  (one-fourth  inch  and  one-eighth  inch, 
respectively)  in  turn,  giving  two  sizes  of  product  which  were  sent  to 
two  different  sets  of  jigs. 
About  4  miles  northeast  of  the  Stella  mine,  at  Pyrites  or  High 
Falls,  the  second  producing  mine  is  located.  Here  a  12-foot  slope 
has  been  run  down  for  230  feet  on  the  dip  of  the  ore  body,  while 
160  feet  of  lateral  drifts  have  been  opened.  The  ore  body  at  this 
point  dips  40°  to  the  west.  As  at  the  Stella  mine,  the  ore  is  inclosed 
in  fine-grained  schist,  but  the  country  rock  at  High  Falls  is  not  the 
normal  gray  gneiss  of  the  region,  but  a  coarse,  well-foliated  gabbro. 
An  old  slope  showed  a  body  of  pyrrhotite  7  or  8  feet  thick  on  the 
hanging  wall,  but  the  new  workings  are  entirely  in  pyrite. 
About  1^  miles  south  of  Richville  a  small  opening  is  being  made 
on  the  west  side  of  the  Rome,  Watertown  and  Ogdensburg  Railroad 
tracks.  The  ore  here  occurs  in  a  body  of  schist  near  its  contact 
with  crystalline  limestone.  The  schist  is  fine  grained,  dark  gray 
to  black,  and  bordered  on  the  west  by  a  series  of  thinly  foliated 
light-gray  gneisses.  The  pyrite  body  at  present  exposed  occurs  in 
the  schist  about  a  foot  from  the  limestone,  and  is  7  feet  thick  at  the 
surface. 
