8i8 
Talc  Resources  and  Production.     (Am.  jour,  Pharm. 
*-      Nov.,  1918. 
TALC  RESOURCES  AND  PRODUCTION  OF  SOUTH 
AFRICA.1 
Talc  has  a  wide  distribution  in  the  older  rocks  of  the  Union  of 
South  Africa,  but  has  hitherto  been  worked  only  in  the  Barberton 
district  of  the  Transvaal  and  in  one  or  two  other  localities.  In  the 
Barberton  district  the  talc  occurs  in  the  form  of  nearly  vertical  bands 
up  to  15  feet  in  thickness,  bounded  by  smooth  joint  planes,  the 
"  country  "  being  a  pale,  dirty  grayish  or  greenish  massive  ultrabasic 
rock,  rich  in  magnesia,  belonging  to  the  Jamestown  series.  The 
purest  form  of  reef  matter  constituting  the  first  quality  of  "  ore  "  is 
a  delicate,  pale  greenish,  subtranslucent  rock  possessing  a  well-devel- 
oped fibrous  structure,  the  slightly  curved  fibers  being  arranged  more 
or  less  parallel  with  one  another.  Dark-colored  varieties,  often  deep 
green  and  quite  opaque,  form  the  second  quality  of  ore.  Gold 
occurs  in  the  talc  as  thin  smears  and  films  on  joint  planes,  and  the 
occurrence  was  originally  worked  as  a  gold  mine.  At  present  gold 
is  a  by-product  of  the  talc-mining  operations.  The  deposits  have 
been  opened  up  by  means  of  shaft  sand  tunnels  and  the  reserves  of 
talc  are  said  to  be  enormous. 
Methods  of  Manufacturing  First-Grade  Talc  Ore. — The 
talc  mined  goes  to  a  dressing  plant,  in  which  the  first  and  second 
grades  of  ore  receive  separate  treatment.  The  better  quality  of 
talc  is  introduced  in  the  form  of  small  lumps  into  a  distintegrator  of 
the  "  cyclone  "  type,  where  it  is  ground  to  a  fine  powder,  which  is 
carried  upward  into  a  vertical  elevator  pipe  by  a  strong  current  of 
air  generated  by  a  blower  attached  to  the  distintegrator.  The  most 
finely  comminuted  talc  passes  out  of  the  top  of  the  vertical  pipe  into 
a  long,  sausage-shaped  vertical  canvas  balloon  and  drops  into  a  re- 
ceiver below  as  soon  as  the  machinery  stops.  The  material  thus  col- 
lected forms  the  best  quality  of  ground  talc.  It  is  used  principally 
for  toilet  and  medicinal  purposes.  The  coarser  talc  powder  that 
does  not  reach  the  top  of  the  vertical  elevator  pipe  is  carried  off  by 
means  of  a  side  piece  to  a  very  fine  horizontal  silk  screen.  The  talc 
remaining  on  this  screen  is  reground ;  that  which  falls  through  con- 
stitutes the  second  grade  of  ground  talc.  It  is  used  for  cleaning  and 
drying  corn  and  other  cereals,  for  making  soap  and  grease,  for  fac- 
1  The  South  African  Journal  cf  Industries,  Pretoria,  June.  Reprinted 
from  Commerce  Reports. 
