156  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   L906,   PART    I, 
ORE  RESERVES. 
Although  a  considerable  area  of  proved  iron-ore  lauds  still  await  I 
development  in  the  Russellville  district,  landowners  and  persons  con-1 
cerned  in  the  iron  trade  display  an  ever-increasing  interest  in  the! 
possible  distribution  of  brown  ores  in  other  parts  of  the  region.    As  : 
a  general  guide  it  may  be  stated  that  similar  geologic  conditions  I 
exist  throughout  the  northern  -portion  of  Franklin  County  and  the 
southern  and  western  parts  of  Colbert  County,  Ala.,  and  in  the  east- J 
ern  part  of  Tishomingo  County,  Miss.;  also  in  parts  of  the  Tennessee! 
River  Valley  in  Tennessee  and  Kentucky.     Therefore  many  deposits 
of  brown  ore  (hat   are  similar  in  character  to  those  at  Russellville 
may  be  revealed   by  prospecting  in   these  localities,      in  Lawrence,] 
Lewis,  and  Wayne  counties,  Tenn.,  such  deposits  have  been  discov-  ! 
ered,  and  ore  is  being  produced  from  them  at   Iron  City,  West   Point, 
Ferro,  Pinkney,  Riverside,  Allen's  Creek,  and  other  points.    Although 
surface  indications  in  the  Russellville  district  have  usually  led  to  the 
opening  of  good  ore  below,  the  surface  indications  above  some  browd 
ore  deposits,  especially  those  in  the  Woodstock,  Ala.,  area,   rarely 
afford  a  true  index  of  the  extent    or  value  of  the  ores  below.      In 
northwestern  Alabama  and  in  the  Tennessee  Valley  in  general  there 
are  no  doubt   local  segregations  of  ore  many  acres  in  extent  that  do 
not    at    all   appear  at    the   surface.     Small   test    wells  3  to  4   feet    in 
diameter  and   20  to  50  feet    deep  may  he  easily  sunk   in  the  loose 
loam  and  gravel  without    involving  the  expense  entailed   by  drilling, 
and  such  tests  yield  the  information  desired.     r! "he  main  points  to  be 
borne  in  mind  are  that   localities  worth  prospecting  for  these  brown 
ores  must   be  underlain  by  limestone  beds  which  are  surfaced  with 
20  to   100  feet   of  loam  and  gravel. 
INDUSTRIAL   DEVELOPMENTS. 
MetJwdsofrninirigandcoTicentrating.     All  the  workings  of  the  district] 
are  open  cuts.  The  scattered  deposits  of  gravelly  ores  of  type  B  are 
worked  profitably  only  on  a  large  scale,  involving  the  use  of  steam 
shovels  to  mine  tin1  ore  and  locomotives  to  haul  it  to  the  washers. 
Some  of  the  richer  deposits  w  ill  pay  if  worked  out  by  hand  and  with 
mule  haulage,  provided  the  washer  can  be  built  near  by.  The  ore  is 
all  concentrated  by  means  ^f  log  washers.  The  ratio  in  cubic  yards 
of  dirt  to  tons  of  ore  washed  varies  from  about  3  to  1  in  the  richer 
deposits  to  L2  to  1  in  the  poorer  deposits.  The  washers  automatically 
remove  most  of  the  clay  from  the  ore  and  all  the  gravel  that  w  ill  pas] 
a  12-mesh  screen;  but  the  results  are  not  thoroughly  satisfactory, 
because  the  washers  fail  to  separate  the  ore  from  the  coarser  gravel 
and  permit  the  loss  of  great  quantities  of  ore  that  is  finer  than  L2-meshj 
The  larger  pebbles  of  gravel  are  removed  by  hand  as  the  ore  passes 
along  a  belt  toward  the  storage  bin.     Water  for  washing  is  obtained 
