LEITH.] 
IKON    ORES    IN    SOUTHERN    UTAH. 
Analyses  of limestone  from  sou/hern.  Utah. 
237 
Si02. 
A1203 
Fe  .. 
P  ... 
ko5. 
haCL 
Per  cent. 
Per  cent. 
0.46 
MgO 
.03 
49.46 
2.67 
0.28 
.03 
50.77 
1.78 
Per  cent. 
3.78 
1.14 
0.62 
.042 
50. 19 
A  partial  analysis  of   the  andesitc  by   George   Steiger  gives  the 
following  result: 
P205 
Fe  . 
0.28 
1.58 
If  the  ore  were  all  to  come  from  the  andesite,  and  it  be  assumed  that 
the  percentage  of  iron  in  the  andesite  shown  by  analysis  be  entirely 
leached  out,  about  607,046,000  cubic  feet  of  andesite  would  be  required 
to  yield  a  million  tons  of  58  per  cent  iron  ore,  or  a  mass  100  feet  thick 
and  less  than  one-half  mile  square,  or  a  mass  10  feet  thick  and  about 
2.7  miles  square. 
If  the  ore  were  all  to  come  from  the  limestone,  and  it  be  assumed 
that  the  percentage  of  iron  in  the  limestone  shown  by  analysis  be 
entirely  leached  out,  about  2,074,000,000  cubic  feet  of  limestone  would 
be  required  to  yield  1,000,000  tons  of  58  per  cent  iron  ore,  or  a  mass 
100  feet  thick  and  less  than  a  mile  square,  or  a  mass  10  feet  thick  and 
about  2.7  miles  square. 
The  unit  of  1,000,000  tons  of  iron  ore  is  taken  for  convenience  in 
calculation  and  not  as  an  estimate  of  tonnage  present. 
The  small  percentages  of  iron  shown  in  the  analyses  of  andesite  and 
limestone  have  not  been  completely  removed  and  furnished  to  per- 
colating solutions,  but  even  then  it  is  apparent  that  the  amount 
furnished  by  leaching  during  the  erosion  of  a  thin  layer  over  a  not 
considerable  area  might  account  for  all  of  the  iron  ore  observed.  This 
is  presented  only  as  a  possibility  and  not  as  a  statement  of  opinion. 
