418 
PLATINUM  OF  BORNEO. 
mountains  and  hilly  districts  is  found,  but  the  relative  proportions 
of  the  three  valuable  minerals  in  it  are  very  different.  Where 
the  diamonds  are  numerous,  gold  and  platinum  are  scarce,  on 
the  contrary,  where  the  grains  of  the  noble  metals  are  abundant, 
the  diamond  is  rarely  found.  Gold  and  platinum  are  also  dis- 
persed over  a  larger  area  than  the  diamonds.  The  diluvial 
deposits  lie  superficially  in  the  higher  districts  of  the  rivers  and 
their  mountain  tributaries ;  in  the  lower  country  the  diluvium 
is  covered  by  the  more  recent  alluvial  deposits  of  the  marshy 
grounds  near  the  coast.  The  diluvium  consists  of  conglomerates 
and  rock  fragments  of  diorite,  gabbro,  quartz  in  different  colors, 
but  the  milky  quartz  is  more  general ;  the  minutest  parts  are 
quartz  sand  and  magnetic  iron-sand.  The  thickness  of  the 
diluvial  stratum  varies  between  a  few  feet  and  as  many  fathoms. 
The  depth  below  the  surface  is  likewise  very  variable  and  ir- 
regular. The  subsoil  is  a  kind  of  loam,  the  thickness  of  which 
is  not  yet  ascertained. 
It  is  very  remarkable,  that  in  some  districts  the  platinum  ore 
contains  grains  of  cinnabar,  especially  at  Playhary.  We  have 
stated  above  that  the  proportion  between  gold  and  platinum  is 
as  10 :  1 ;  but  this  relation  is  very  variable,  because  at  Katapan 
it  is  5;  1,  at  Soengi  Matjan  20:  1. 
Last  year  I  received  a  sample  of  the  Borneo  platinum  ore, 
which  is  now  beginning  to  attract  the  attention  of  our  commercial 
society.    The  results  of  my  analysis  are  as  follows  : — 
Platinum  Ore  of  Banjarmassxn. 
Separated  by  solution  in  J  Iron  oxide  and  iron  1.13 
hydrochloric  acid.       \  Copper,       .       .  0.50 
Osmium,   1.15 
Gold,   3.97 
Platinum,   70.21 
Iridium,   6.13 
Palladium,         .       .       .       .       .       .  1.44 
Rhodium,   0.50 
Iron,   5.80 
Copper,   0.34 
Insoluble  in  aqua  regia:  Osmiridium  and 
minerals,  8.83 
The  osmium  was  separated  by  distillation  as  described  by 
Berzelius.    The  analysis  was  executed,  following  the  method  of 
