MINERAL  PRODUCTS.

33

worked  since  1845.  The  barite  deposits  of  Bedford,  Campbell,  and
Pittsylvania  counties,  in  the  south-central  part  of  the  State,  centered ­
  about  Evington  and  Toshes,  are  in  highly  altered  crystalline
rocks  formed  from  old  sedimentary  and  igneous  rocks.  Barite  has
been  found  associated  with  similar  rocks  in  six  other  counties  in  the
Piedmont  region,  but  has  not  been  mined  to  any  considerable  extent.
In  southwestern  Virginia,  in  Tazewell,  Wythe,  Bussell,  and  Smyth
counties,  barite  occurs  in  the  Cambrian  and  Ordovisian  limestones
or  their  residual  clay.
Deposits  of  barytes  are  known  in  Mariposa  County,  in  California  ;
in  Clark,  Elko,  Mineral,  and  Nye  counties,  in  Nevada;  in  Blaine
County,  in  Idaho  ;  and  in  Alaska.  Most  of  the  deposits  in  the  Western ­
  States  are  undeveloped,  as  there  has  apparently  been  a  scanty
market  for  this  material  ill  that  region,  and  railroad  freight  rates
have  not  permitted  western  barite  to  compete  with  either  foreign  or
domestic  barite  in  the  principal  centers  of  use  in  the  East.  In  1913
E.  F.  Burchard,  of  the  United  States  Geological  Survey,  discovered
a  considerable  deposit  of  barite  associated  with  quartzite  schists  on
Castle  Island,  in  the  Duncan  Canal,  40  miles  northwest  of  Wrangell,
in  Southeastern  Alaska.
Witherite,  or  barium  carbonate  (BaCO ;i ),  is  used  in  the  manufacture ­
  of  glass  and  porcelain,  and  in  the  preparation  of  oxygen,  barium
salts,  boiler  compounds,  vermin  poisons,  and  green  fire.  It  is  a
dense,  soft  white  powder,  which  is  poisonous.  So  far  as  is  known
to  the  United  States  Geological  Survey,  there  are  no  deposits  of
witherite  of  commercial  size  in  the  United  States.  Commercial
deposits  have  been  mined  in  England,  Silesia,  Hungary,  Styria,  and
Russia.  Barium  carbonate  can  be  prepared  by  igniting  a  mixture  of
10  parts  of  powdered  barite,  2  parts  of  charcoal,  and  5  parts  of
potassium  carbonate.  Potassium  sulphide  and  barium  carbonate
result  from  the  reaction,  and  may  be  separated  by  water,  as  barium
carbonate  is  very  sparingly  soluble  in  water.  Another  method  of
preparing  barium  carbonate  is  by  heating  100  parts  of  powdered
barium  sulphate  with  250  parts  of  sodium  carbonate  and  200  parts
of  water  in  autoclaves  at  5  atmospheres  pressure.
phosphate  rock.
Of  the  mineral  fertilizers  phosphate  is  the  one  of  which  the  United
States  has  large  reserves.  The  fields  and  gardens  of  Europe  largely
depend  on  this  supply,  nearly  one-half  of  our  production  going  to
trails-Atlantic  ports.  The  great  bulk  of  the  phosphate  rock  exported
is  obtained  in  Florida  and,  of  course,  includes  chiefly  the  better
grades.
Though  phosphate  rock  is  an  important  item  of  export,  interruption ­
  of  the  foreign  sales  can  not  be  regarded  as  a  national  calamity.

59170°—Bull.  599—14  3