INVESTIGATION  OF  BLACK  SANDS  FROM  PLACER 
MINES. 
By  David  T.  Day  and  K.  II.  Richards 
INTRODUCTION. 
One  of  the  earliest  notes  concerning  the  occurrence  of  gold  in  California^  points  out  the 
probable  occurrence  of  gold  in  the  black  sands  of  the  Pacific  seacoasl  .and  also  points  out  the 
difficulty  in  the  separation  of  the  grains  of  gold  from  the  accompanying  heavy  minerals. 
Among  the  early  prospectors  for  gold  in  California  this  difficulty  of  separating  gold  from 
black  sands  was  recognized  and  the  black  sands  were  avoided.  Some  account  of  the  minerals 
making  up  these  sands  was  given  by  B.  Silliman,&  who  showed  that  the  black  sands  of  Butte 
County,  Ca I.,  contained  platinum  and  iridosmine,  magnetite,  zircon,  chromite,  garnet ,  rutile, 
diamond,  topaz,  epidote,  pyrite,  and  limoriite.  This  is  one  of  the  earliest  references  to  the 
occurrence  of  platinum  on  the  wesl  coast.  Following  Silliman,  W.  P.  Blake  recognized 
platinum  as  of  frequent  occurrence  in  the  black  sands  of  the  California  sea  beach,  between 
Cape  Mendocino  and  the  Oregon  line.  The  attention  thus  called  to  the  occurrence  of  plati- 
num resulted  in  considerable  mining  designed  to  extract  gold  from  these  sands  and  fre- 
quently a  small  amount  of  plat  inuni  was  saved.  The  platinum  was  found  to  contain  also  con- 
siderable proportions  of  iridosmium  and  iridium,  for  which  there  was  no  adequate  sale.  Only 
a  small  amount  of  iridosmium  was  bought  for  the  purpose  of  picking  out  points  for  gold  pens, 
the  rest  having  no  regular  market. 
While  the  knowledge  of  the  occurrence  of  platinum  was  extended  by  the  placer  miners  to 
Del  Norte,  Humboldt,  Trinity,  Siskiyou,  and  other  counties  in  California,  and  to  Coos,  Curry, 
Jackson,  and  Josephine  counties  in  Oregon,  as  well  as  to  considerably  richer  localities  in 
British  Columbia,  notably  in  Granite  Creek,  a  tributary  of  Tulameen  River,  little  interest 
was  taken  by  them  in  saving  the  platinum,  on  account  of  its  small  value.  In  1897,  however, 
a  demand  suddenly  arose  for  osmium  from  the  Welsbach  Light  Company,  which  needed  a 
supply  for  making  the  filament  of  the  osmium  incandescent  electric  light.  In  1897  and  1898 
one  of  the  writers  examined  various  placers  in  Shasta,  Tehama,  Trinity,  Humboldt,  Siski- 
you, Del  Norte,  San  Luis  Obispo,  and  other  counties  in  California,  in  Coos,  Curry,  Jackson, 
and  Josephine  counties  in  Oregon,  and  at  Granite  Creek  in  British  Columbia.  From  these 
occasional  visits  it  became  evident  that  even  with  the  new  market  for  the  osmium  found 
with  the  platinum,  no  adequate  supply  of  platinum  would  be  obtained  until  a  system  of 
separating  and  utilizing  the  accompanying  minerals  in  the  black  sand  should  be  developed. 
a  Dr.  Edward  Everett  Hale  has  furnished  this  reference  from  Shellrocke's  Voyages  to  California, 
published  in  London  in  1742. 
6  Am.  Jour.  Sci.,  3d  ser.,  vol.  6,  1873,  p.  132. 
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