HESS    AM 
GBATON 
;VD]  OCCURRENCE    AND    DISTRIBUTION    OF    TIN.  171 
The  accompanying  minerals  are  tourmaline,  topaz,  fluorspar,  wol- 
framite, scheelite,  molybdenite,  beryl,  arsenopyrite,  magnetic,  man 
ganese  oxides,  and  chlorite. 
There  are  several  series  of  tin-bearing  gravels,  some  of  which  are 
Eocene  as  shown  by  plant  remains  in  the  accompanying  clays. 
These  Eocene  gravels  have  beer  preserved  by  lava  flows.  Flow- 
occurred  at  different  periods,  and  gravels  formed  during  the  intervals 
were  covered  by  succeeding  flows.  These  old  gravels  contain  much 
zircon,  topaz,  beryl,  garnet,  emerald,  and  sapphire,  and  it  was  in 
digging  for  these  gems  thai  the  tin  was  discovered.  There  is  also 
a  little  gold  in  the  gravels,  which  vary  from  10  feci  l,  one-half  mile 
in  width,  and  are  from  1  \  to  79  feet  thick.  The  pay  streaks  average 
from  ().'.)  to  7  per  cent  cassiterite,  hut  there  is  generally  a  heavy  over- 
burden of  barren  or  almost  barren  gravel,  although  in  some  places 
tin  ore  may  occur  in  the  top  gravels. 
Dredgers  have  now  been  introduced  in  this  region  for  extracting 
the  stream  tin. 
During  the  year  1903  New  South  Wale-  produced  842  ton-  of  tin 
and  exported  613  ton-  of  ore. 
Victoria  i.-  but  a  -mall  producer  of  tin.  although  in  1891  it  pro- 
duced 1.(.>'.>1  ton-  of  tin  ore.  In  1892  the  output  fell  to  457  ton-,  and 
in  1903  hut  36  ton-  were  produced.  Of  this  amount  19  ton-  were 
saved  by  gold  dredgers  at  Beechworth,  L3  tons  at  Chiltern  and  Ruth- 
erglen  in  mining  auriferous  gravels,  and  4  tons  were  obtained  by 
luicing  in  the  Upper  Yarra  district. 
No  reins  are  being  worked,  although  some  are  known  near  Mitt  a 
Mitta.  close  to  the  New  South  Wales  border. 
Smith  A  ust mint  has  not  been  a  large  producer,  but  in  1902  142 
:onsof  tin  ore  were  produced,  part  of  which  came  from  the  Northern 
erritory.0 
West  Australia. — Tin  ore,  both  as  stream  tin  and  in  veins,  occurs 
n  three  widely  separated  districts — at  the  head-  of  the  Bow  and  Len- 
nard  rivers  in  the  Kimberley  district;  at  Brockman-  Soak.  Western 
3haw, Moolyella, Coglegong, and Wodgina  in  the  Pilbarra  goldfields; 
in«l  at  Greenbushes  in  the  southwestern  portion  of  the  colony. 
The  Moolyella  diggings,  winch  have  been  the  mosl  important  of 
he  Pilbarra  goldfields,  are  all  detrital,  and  were  derived  from  veins 
arrying  low  j percentages  of  ore. 
The  entire  area  i-  occupied  by  an  intru-ive  quartz-feldspar-micn 
granite  that  often  becomes  coarse  grained.  Its  age  i-  unknown.  In 
dace-  pegmatite  carries  a  low  percentage  of  cassiterite,  and  its  weath- 
ring  has  furnished  the  tin  for  the  placers.     The  placers  are  about 
"British  Ulm-  Book,  Mines  and  Quarries,  Genl.   Kept,  and  Statistics,  Pari    IV,  Colonial 
nd  Foreign  Statistics  lor   L902,   1904,  i>.  316. 
