France  and  the  other  Mediterranean  countries  have  an  ample  supply  in
Algeria  and  Tunis.  Germany  formerly  possessed  rich  deposits  of  phos-
phate on  Angaur  Island,  in  the  Pelew  group,  Polynesia,  and  on  Pleasant
and  Ocean  islands,  but  so  far  as  known  now  lacks  a  source  of  supply.
Japan  has  a  large  supply  of  high-grade  phosphate  at  her  disposal  on
Rasa  and  Angaur  islands.
SUMMARY

The  principal  use  of  phosphate  rock  is  as  an  ingredient  of  fertilizers.
Lesser  quantities  are  consumed  in  the  manufacture  of  phosphoric  acid,
in  phosphorus  used  in  military  operations,  in  the  manufacture  of  matches,
and  in  metallurgy.  Both  natural  and  artificial  substitutes  are  available
for  many  of  the  uses  of  phosphate  rock.
Phosphate  rock  is  a  sedimentary  deposit  containing  phosphate  of
lime.  It  occurs  as  a  hard  rock  between  beds  of  sandstone  or  shale,  as
amorphous  nodular  phosphates  in  stream  deposits,  and  as  a  residuum
from  the  decomposition  of  phosphatic  dolomite,  limestone,  and  other
phosphate-bearing  rocks.  The  porous  limestone  of  tropical  islands,
where  it  is  permeated  with  phosphate  leached  from  guano,  is  commonly
classed  as  phosphate  rock.
The  phosphate  rock  deposits  of  present  commercial  importance  are
situated  in  the  United  States,  Algeria,  Tunis,  Egypt,  and  the  islands  of
the  Indian  and  South  Pacific  oceans,  the  United  States  possessing  by
far  the  largest  reserves.     Smaller  deposits,  either  undeveloped  or  nearly


410  POLITICAL  AND  COMMERCIAL  GEOLOGY

exhausted,  are  in  Canada,  Venezuela,  Chile,  Belgium,  France,  Russia,
England,  Spain,  South  Australia,  and  New  Zealand.
During  the  war  the  exports  of  phosphate  rock  from  the  United  States
decreased  greatly.  With  the  return  to  normal  conditions,  however,  the
United  States  should  experience  little  difficulty  in  becoming  once  more
the  principal  source  of  phosphate  rock.
