LINdgrkn.]   PRODUCTION    OF    GOLD    IN    UNITED    STATES    IN    1904.  35 
at  any  rate  these  contribute  a  very  small  part  to  the  total  production. 
In  Alaska  the  consensus  of  opinion  among  geologists  seems  to  be  that 
the  Yukon  placers  are  concentrated  from  older,  possibly  Paleozoic, 
A^eins,  Avhile  a  smaller  part  is  derived  from  veins  of  the  same  age  as 
those  of  the  principal  California  belt. 
The  veins  in  Tertiary  lavas — andesites,  basalts,  and  rhyolites — con- 
tain gold  that  is  so  finely  divided  or  so  combined  chemically  with 
other  elements  that  it  does  not  readily  accumulate  in  the  stream  chan- 
nels beloAv  the  deposits,  even  if  grade  and  other  conditions  are  favor- 
able. 
The  production  of  placer  gold  from  the  Appalachian  belt  is  prob- 
ably about  the  same  as  last  year,  or  $30,000.  This,  as  well  as  the  few 
ounces  from  Wyoming,  is  derived  from  the  oldest  deposits  known  in 
the  United  States — generally  considered  pre-Cambrian,  although 
some  of  them  may  be  of  slightly  younger  age. 
Summing  up,  we  have,  then : 
Placers  from  pre-Cambrian  deposits $38,000 
Placers  from  Paleozoic  and  Mesozoic  deposits 11,802,000 
Placers  from  Tertiary  deposits 1,000,000(7) 
Total 12,  900,  000 
In  the  majority  of  cases  the  placer  deposits  are  of  Quaternary  or 
early  Tertiary  age.  The  oldest  deposits  exploited  are  the  Eocene  and 
Miocene  channels  of  the  Sierra  Nevada,  generally  buried  underneath 
heavy  flow  of  andesite  breccia.  These  contributed  about  $600,000  in 
1903,  an  unusually  small  amount,  although  the  production  has  been 
decreasing  slowly  for  many  years. 
GOLD   DERIVED   FROM   QUARTZOSE,  OR  DRY,  ORES. 
Auriferous  quartz  veins  of  pre-Cambrian  age  are,  as  far  as  known, 
confined  to  the  Atlantic  States,  Michigan,  South  Dakota,  and  Wyom- 
|  ing.  Some  of  them  may  possibly  be  of  somewhat  later,  or  Paleozoic, 
age.  In  1904  the  yield  from  these  veins  amounted  to  $325,100,  the 
bulk  of  it  coming  from  North  Carolina,  South  Carolina,  and  Georgia. 
Part  of  it  is  derived  from  gold-bearing  pyrites  and  a  very  small 
amount  from  gold-bearing  copper  ores.  This  output  is  somewhat 
larger  than  that  of  1903. 
In  South  Dakota  the  great  low-grade  deposit  of  the  Homestake 
ine  is  considered  to  be  of  pre-Cambrian  age;  its  output  has  greatly 
increased  and  is  reported  to  be  $4,950,558  for  1904.  The  small  pro- 
duction of  Wyoming  should  probably  also  be  credited  to  the  same 
class  of  deposits;  a  fraction  of  it  is  derived  from  the  pre-Cambrian 
popper  ores  of  the  Encampment  district. 
The  total  production  of  gold  from  pre-Cambrian  veins  for  1904 
fs  estimated  at  $5,454,158. 
i  a 
ill 
