104 
CONTRIBUTIONS   TO   ECONOMIC    GEOLOGY,  1905. 
CALIFORNIA. 
Nine  out  of  the  57  counties  of  California  contain  producing  copper  mines.     Their  pro 
duction  for  1904  is  shown  in  the  following  table: 
Production  of  copper  in  California  in  1904,  by  counties. 
County. 
Quantity. 
Value. 
Gold  in 
copper 
ores. 
Silver  ii 
copper 
ores. 
Pounds. 
14,000 
2,611,660 
8,408 
10,300 
9,500 
600,000 
154,  477 
26,  438, 145 
7,300 
107,800 
$1,400 
277, 165 
850 
1 ,  300 
1,140 
72,000 
15,020 
3,402,517 
930 
13, 700 
$74,702 
50 
$64, 3T 
10' 
Mariposa 
40 
in.  ooo 
50,503 
369,813 
2i 
9, 121 
San  Bernardino 
13,02; 
394, 594 
29,961,590 
3,786,022 
Two  new  smelters  in  Shasta  County  added  t<>  (lie  output  for  1905,  while  the  Mountain 
Copper  Company  has  built  new  reduction  works  at  Martinez,  on  San  Francisco  Bay,  at  ai 
cost  of  about  $1,000,000.  Calaveras  County  has  seen  the  reopening  of  one  of  the  most 
productive  of  the  older  copper  mines  of  the  State,  and  extensive  reduction  works  begun  in 
1904  are  now  said  to  be  nearly  completed.  Placer  County  gave  a  considerable  return  from 
the  new  property  opened  in  1904,  and  various  other  properties  scattered  throughout  the 
copper  bolt,  lying  on  the  western  flanks  of  the  Sierra  Nevada,  are  being  equipped  and 
developed,  so  that  the  outlook  for  an  increased  copper  production  is  bright. 
Nearly  every  county  contains  copper  deposits,  but  the  known  deposits  of  economic  im- 
portance are  confined  to  four  groups:  (1)  Shasta  County,  (2)  the  western  flanks  of  the 
Sierra  Nevada,  (3)  the  Coast  Range,  and  (4)  the  deserts  of  southeastern  California.  Up 
to  the  present  time  almost  the  entire  production  comes  from  Shasta  County,  in  the  north- 
central  part  of  the  State.  The  Foothill  copper  belt  of  the  western  flanks  of  the  Sierra  is 
nearly  400  miles  long,  and  contains  many  old  and  formerly  productive  mines.  One  of  these, 
at  Copperopolis,  has  lately  been  reopened.  The  Coast  Range  deposits  extend  southward 
for  150  miles  from  the  Oregon  line,  a  number  of  old  and  formerly  productive  mines  existing 
in  Del  Norte  County. 
The  western  or  Iron  Mountain  belt  of  Shasta  County  lies  3  to  6  miles  west  of  Sacra- 
mento River,  between  Redding  and  Kennett.  The  eastern  or  Bully  Hill  belt  lies  east  of 
Sacramento  River,  north  of  Pit  River,  and  west  of  Squaw  Creek,  near  Copper  City  and 
Delamar.  According  to  Aubury  a  the  ore  bodies  of  the  western  belt  occur  on  or  near  the 
contact  between  granite-porphyry  and  metamorphic  slates  or  schists.  Those  of  the  eastern 
belt  lie  partly  in  schists  (Devonian  metamorphic  rocks),  partly  in  porphyry,  but  mainly  on 
the  contact  between  the  two. 
The  region  has  been  geologically  mapped  by  J.  S.  Diller,  whose  preliminary  report  on  the 
geology  of  the  copper  deposits  appeared  in  1903.  b  He  states  that  the  ore  deposits  occur 
in  two  areas  of  ancient  volcanic  lavas,  probably  of  Carboniferous  age,  mostly  a  metarhyo- 
lite  rich  in  soda.     The"  sedimentary  rocks  include  Triassic  shales  and  limestones  in  the  Bully 
a  Bull.  California  State  Mining  Bureau  No.  23. 
b Contributions  to  Economic  Geology,  1902;  Bull.  U.  S.  Geol.  Survey  No.  213,  1903,  p.  123.  See  also 
Bull.  U.  S.  Geol.  Survey  No.  225,  1904,  p.  172. 
