184  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
In  the  face  of  such  conditions  as  to  brown-ore  supply,  it  would  seem  wise  to  commence 
active  and  careful  exploration  of  the  other  two  classes  of  ore  known  to  exist,  in  workable 
quantities,  in  the  State.  These  are  (1)  the  Clinton  red  or  fossil  ores  of  western  Virginia, 
and  (2)  the  magnetites  of  the  Blue  Ridge  and  Piedmont  districts.  Neither  of  these  classes* 
of  ore  has  as  yet  been  given  proper  consideration. 
At  present  from  100,000  to  200,000  tons  of  ore  are  shipped  into  Virginia  furnaces  from 
Tennessee,  North  Carolina,  and  the  Lake  Superior  districts,  a  fact  which  must  be  borne  in 
mind  when  comparing  the  iron-ore  and  pig-iron  statistics  given  later.  Lake  Superior  ores' 
cost  from  8  to  10  cents  per  ton  per  unit  of  iron  when  they  reach  the  Virginia  furnaces,  asl 
compared  with  3  to  5  cents  per  ton  per  unit  for  the  native  brown  ores. 
The  following  data  in  cost  of  iron  production  in  various  States  have  been  calculated  from 
figures  given  in  the  reports  of  the  Twelfth  Census  (1900).  The  total  costs  as  here  givent 
include  raw  materials  (ore,  fuel,  flux,  etc.),  wages,  salaries,  and  repairs. 
Cost  of  production  of  coke  iron,  per  ton,  1900. 
Alabama $8.12 
Tennessee 9. 97 
Illinois 10. 12 
Pennsylvania 11.23 
Virginia 12. 12 
The  Alabama  and  Virginia  costs  above  given  have  been  checked  with  a  number  of 
detailed  cost  sheets  kindly  furnished  by  several  companies  iw  those  States,  and  it  is  believe! 
that  the  averages  given  can  be  accepted  as  correct  enough  for  present  purposes.  They  may," 
nf  any  rate,  be  profitably  compared  with  the  estimates  to  be  found  in  prospectuses. 
The  iron-ore  and  pig-iron  production  of  Virginia  are  summarized  for  the  years  1S<)<)  to 
11)05,  inclusive,  in  the  following  table: 
Iron-ore  and  pig-iron  production  of  Virginia  and  West  Virginia. 
Year. 
1899 
1900 
1901 
1902 
1903 
1904 
1905 
Brown  ore, 
968,  L43 
918,  L57 
910,214 
953,  L28 
764,948 
328,853 
a  702, 000 
Red  hema- 
17, 173 
3,664 
L3,  156 
31,677 
31,069 
LT,  952 
a  45, 000 
Magnetite. 
1,1  CO 
2,024 
3,153 
4,004 
3,  448 
3,000 
Total  iron 
ore. 
986, 470 
921,821 
925, 394 
987,958 
801, 1G1 
550,253 
a  750, 000 
Total  pig 
365, 491 
490,611 
448, 002 
037,216 
544.034 
310,526 
510,211 
a  Estimated.    All  other  figures  are  exact. 
ORISKANY   BROWN   ORES. 
In  the  counties  of  Allegheny,  Augusta,  Rockbridge,  Bath,  Botetourt,  and  Craig,  and,  to 
a  less  extent,  in  other  areas  of  central  western  Virginia,  large  deposits  of  brown  iron  ore  arj 
associated  with  certain  beds  of  the  Silurian  rocks.  The  deposits  are  frequently  overlain  bl 
the  Oriskany  sandstone,  and  most  observers  have  considered  the  ores  to  be  original  deposit! 
in  that  formation,  so  that  the  term  "Oriskany  ores"  has  come  into  common  use.  Careful 
examination,  however,  shows  that  the  ores  are  replacements,  mainly  of  Ihe  "  Belderbergj 
or  Lewistown  limestone,  but  also  of  the  adjacent  beds  of  the  Oriskany.  As  a  mutter  of 
convenience  the  term  "Oriskany  ores"  may  well  be  retained,  even  though  it  is  somewhat 
misleading. 
Early  in  the  field  season  of  1905  the  writer  commenced  work  on  the  ores  of  this  district, 
studying  their  occurrence,  character,  and  origin.  After  the  complel  ion  of  this  general  work, 
Mr.  R.  J.  Holden,of  the  Virginia  Geological  Survey,  was  detailed  t<>  map  certain  of  the  more 
important  ore  deposits  on  a  large  scale,  while  Mr.  J.  S.  Grasty  took  up  general  geologic 
