198  CONTRIBUTIONS    TO    "ECONOMIC    GEOLOGY,   1903.  [bill. 225. 
schists  seen  southward.  There  are  two  adjoining  mines— the  Union 
and  the  Eureka. 
The  Union  mine  was  first  opened  in  1866.  The  production  from 
that  year  up  to  1881,  inclusive,  amounted  to  31,501  tons  of  ore,  carry- 
ing 8.5  per  cent  to  10  per  cent  copper.  In  1879  and  1880  a  total  of 
5,712,604  pounds  of  fines,  carrying  2.7  percent  to  4.5  per  cent  copper, 
was  sent  to  the  Copperfield  smelter. 
The  property  is  developed  by  an  inclined  shaft  about  900  feet  long, 
or  766  feet  below  the  adit  level.  Down  to  a  depth  of  300  feet  four 
overlapping  lenses  of  ore  were  worked.  The  shaft  leaves  the  ore  at 
a  depth  of  500  feet  on  the  incline  below  the  adit  level,  and  continues 
downward  in  the  hanging-wall  schists.  The  lower  ore  bodies  are 
developed  by  winzes  sunk  in  the  foot  wall.  Assay  of  a  sample  of 
selected  ore  from  the  dump  showed  8.15  per  cent  copper,  25  per  cent 
silica,  with  traces  of  gold  and  0.3  ounces  silver  per  ton.  The  vein 
has  a  north-south  course,  dips  30°  E. ,  and  has  an  average  thickness 
of  8  feet. 
The  Eureka  mine  lies  south  of  the  Union.  It  has  been  opened  by 
an  inclined  shaft  said  to  be  500  feet  deep,  wTith  two  adit  levels,  the 
uppermost  cutting  the  vein  at  a  depth  of  200  feet  below  the  outcrop. 
The  vein  is  said  to  average  8  feet  in  thickness,  and  about  100  feet  in 
horizontal  extent.  Selected  samples  of  the  rich  ore  contained  19.65 
per  cent  copper,  19.52  per  cent  silica,  and  0.76  ounces  of  silver  per 
ton  of  ore. 
COMPARISON  WITH  OTHER  REGIONS. 
The  similarity  of  these  deposits  to  those  of  Ducktown,  Tenn.,  has 
already  been  remarked.  They  are  also  very  similar  in  form  and  min- 
eral contents  to  the  deposits  found  in  the  province  of  Quebec,  Canada, 
which  lie  almost  due  north  of  the  Vermont  belt.  Almost  all  previous 
writers  have  remarked  upon  this  fact,  and  have  attempted  to  correlate 
the  deposits  as  a  geologic  unit,  basing  their  conclusions  on  the  fact 
that  the  rocks  are  similar  and  occur  along  the  strike  of  the  schists. 
The  danger  of  such  hasty  correlation  is  shown  by  the  recent  study  of 
the  Quebec  deposits  by  Dresser.  His  work  proves  the  talcose,  mica- 
ceous, or  chloritic  schists  to  be  disguised  volcanics  of  early  geologic 
age  and  variable  composition,  but  largely  diabasic  in  character.  The 
so-called  sandstones  of  the  Ascot  belt,  in  which  the  Capelton,  Suf- 
field,  and  Sherbrooke  mines  occur,  is  really  a  quartz-porphyry,  while 
the  westerly  belt,  embracing  the  copper  mines  of  Acton,  Upton,  Rox- 
ton,  Wickham,  and  St.  Flavien  are  in  limestones,  with  associated, 
black,  graphitic  shales  intruded  by  igneous  rocks,  the  copper  ores  being 
near  and  sometimes  in  igneous  masses. 
