COPPER    MINES    0¥    THE    UNITED    STATES TENNESSEE.        1  19 
of  pyrite  and  pyrrhotite.  They  form  lenticular  masses  inclosed  in  altered  and  schistose 
igneous  rocks,  but  as  the  locality  has  not  been  visited  by  any  member  of  the  Survey  no 
detailed  information  is  available. 
In  eastern  Oregon  there  arc  a  number  of  copper  properties  which  have  attracted  more 
or  less  attention  for  some  years  past.  They  occur  in  the  Blue  Mountain  region,  and  most 
of  the  deposits  are  contained  in  Triassic  lavas,  mainly  basaltic,  interbedded  with  sedimen- 
tary rocks  of  the  same  age.  Three  types  have  been  distinguished  by  Lindgren— the  Seven 
Devils  type,  the  Tourmaline  type,  and  the  Snake  River  type. 
The  first  named  includes  contact  deposits  of  irregular  bodies  of  chalcopyrite  and  bornite, 
lying  between  limestone  and  diorite.  The  ores  contain  a  gangue  of  garnet,  epidote,  and 
other  contact  minerals.     The  only  example  of  this  type  occurs  near  Medical  Springs. 
The  Tourmaline  type  is  characterized  by  chalcopyrite  and  p}uite  associated  with  a  gangue 
of  quartz  and  tourmaline,  the  ores  occurring  in  fissure  veins  and  irregular  replacements. 
The  Copperopolis  mine,  in  the  Quartzburg  district,  and  the  Jessie  vein,  in  the  Mineral 
district,  are  of  this  character. 
The  Snake  River  deposits  occur  in  the  canyon  of  that  stream,  southwest  of  Seven  Devils, 
80  miles  from  Baker  Gity.  The  type  consists  of  deposits,  largely  of  metasomatic  origin, 
of  finely  distributed  copper  glance,  bornite,  and  rarely  of  chalcopyrite,  in  Triassic  lavas  or 
tuffs.  The  distribution  of  the  sulphides  is  irregular,  but  commonly  follows  well-defined 
directions,  probably  determined  by  joint  systems,  though  no  sharply  defined  fissures 
could  be  observed.  The  gangue  minerals  arc  quartz,  epidote,  actinolite,  or  chlorite.  At 
Copper  Union  and  near  Ballards  Ferry,  in  the  Snake  River  Canyon,  the  deposits  are  epidotie. 
In  the  Snowstorm  mine,  near  Sanger,  the  rock  is  a  diabase  and  the  ore  aetinolitic.  The 
Iron  Dike  and  River  Queen  deposits  are  chloritic. 
^The  Copper  Butte  district  contains  a  number  of  deposits  in  basaltic  rocks  of  Triassic  age. 
Among  the  copper  deposits  noted  in  the  foregoing  paragraphs  there  are  no  producing 
mines,  though  small  shipments  of  high-grade  ores  have  been  made  from  one  or  two  of  the 
prospects.  In  general  it  may  be  said  that  the  ores  are  of  low  grade  and  that  the  zones  will 
not  average  more  than  1  or  2  per  cent  of  copper. 
TENNESSEE. 
The  copper  production  of  Tennessee  comes  entirely  from  the  Ducktown  district.  The 
output  for  1905  showed  only  a  slight  increase  over  that  of  1904,  as  the  four  new  furnaces 
were  not  put  in  commission.     The  Tennessee  Company  produced  7,977,982  pouunds. 
The  production  for  the  last  six  months  of  the  year  averaged  about  1,000,000  pounds  of 
copper  per  month,  the  recovery  being  35  pounds  of  copper  per  ton  of  ore.  The  Burra 
Burra  ore  carries  2.3  per  cent  of  copper,  0.33  ounce  of  silver,  0.001  ounce  of  gold,  and  0.01 
per  cent  of  tellurium  and  selenium  per  ton.  It  is  concentrated  50  to  1  by  matting  and 
converting  to  a  pig  copper  carrying  99.4  per  cent  of  copper,  12.5  ounces  of  silver,  0.025 
ounce  of  gold,  0.01  per  cent  of  tellurium  and  selenium,  and  0.0007  per  cent  of  arsenic. 
GEOLOGY. 
The  Ducktown  district  is  in  the  extreme  southeast  corner  of  the  State,  on  one  of  the  lines 
of  the  Louisville  and  Nashville  Railroad.  The  deposits  outcrop  on  a  small  upland  plateau 
inclosed  by  higher  mountains  and  trenched  by  stream  channels.  The  country  rock  is  a 
thinly  foliated  mica-schist  with  occasional  intercalated  layers  of  gneiss.  The  rocks  are 
commonly  regarded  as  part  of  the  "Ocoee"  series  of  Cambrian  age,  but  they  differ  from 
the  rocks  of  this  series  as  exposed  in  the  Hiwassee  gorge.  The  foliation  runs  north-northeast 
and  the  beds  dip  50°  SE.  Microscopic  study  by  Kemp  a  shows  the  rocks  to  consist  of 
biotite  and  quartz,  indicating  a  sedimentary  origin;  the  conclusions  reached  by  Keith  are 
in  accord  with  this. 
a  Trans.  Am.  Inst.  Min.  Eng.,  vol.  31,  1901,  p.  244. 
