330  CONTRIBUTIONS   TO   ECONOMIC    GEOLOGY,  1904.        [bull.  260. ' 
contains  many  thin  branching-  veins  of  white  calcite,  which  contrasts, 
.strikingly  with  the  deep  red  body  of  the  ore. 
THE    BROWN    ORE. 
Distribution,  geologic  relations,  and  development. — If  it  should 
attempted  to  give  a  general  rule  for  the  distribution  of  workable 
deposits  of  brown  ore,  it  might  be  said  that  such  deposits  have  inva- 
riably been  found,  in  the  Brookwood  quadrangle  at  least,  directly 
associated  with  two  groups  of  rocks — the  Cambro-Ordovician  lime- 
stone and  dolomite  and  the  Cretaceous  or  Tertiary  sands  and  clays. 
The  brown  ores  occur  in  irregular  pockets  or  banks  in  sandy  clay  on 
other  unconsolidated  material  that  overlies  dolomite  or  limestone  beds. 
In  most  cases  the  ore-bearing  materials  are  clearly  of  Cretaceous 
or  later  age.  In  certain  cases  the  ore  may  occur  in  residual  cla^J 
which  results  from  the  decomposition  of  the  underlying  dolomite  orl 
limestone.  The  valuable  brown  ores  are  widespread  in  Roups  Valley] 
from  the  vicinity  of  Bucksville  southwestward  to  the  locality  where 
the  limestones  finally  disappear  below  Cretaceous  deposits  along  Bid 
Sandy  Creek  near  the  old  Clements  place.  Important  brown  ore: 
deposits  have  been  observed  during  this  survey  or  reported  by  tha 
Alabama  Geological  Survey  in  sees.  19,  30,  and  31,  T.  20  N.,  R.  5  W.i 
sees.  25  and  36,  T.  20  N.,  R.  G  W. ;  sees.  1,  2,  3,  9,  10,  11,  12, 14,  15,  and 
17,  T.  21  N.,  R.  6  W. ;  sec.  32,  T.  21  N.,  R.  7  W. ;  sec.  17,  T.  22  N.,  Rj 
7  W.,  and  sec.  24,  T.  22  N.,  R.  8  W.  In  this  area  are  the  well-knowil 
active  open-cut  mines  at  Goethite,  Greeley,  Reno,  and  Giles  and  the 
extensive  preliminary  surface  stripping  that  is  being  done  by  the 
Tennessee  Coal,  Iron,  and  Railroad  Company  between  Reno  and 
Greenpond.  In  the  valley  between  the  mines  near  Woodstock  and 
the  most  southwesterly  showings  of  ore  there  is  an  area  of  approx- 
imately 40  square  miles  that  probably  has  not  been  thoroughly 
tested,  and  there  is  reason  to  believe  that  rich  deposits  of  brown  oil 
may  be  found  in  such  parts  of  this  area  as  are  surfaced  with  thin 
Cretaceous  or  later  beds  overlying  limestone  or  dolomite.  It  is  not 
so  probable  that  similar  deposits  would  be  found  near  the  contact 
of  the  limestone  and  the  clays  where  the  clays  lie  several  hundred 
feet  deep ;  but  where  these  unconsolidated  deposits  are  not  more  than 
50  to  100  feet  deep  prospecting  can  be  most  conveniently  and  econom- 
ically accomplished.  The  deposits  are  very  variable,  and  the  miner's 
maxim,  "  No  one  knows  much  about  a  brown-ore  bank  beyond  the 
length  of  his  pick,"  is  repeated  here  for  the  sake  of  emphasizing  the 
importance  of  thoroughly  prospecting  a  piece  of  ground  and  of 
becoming  thoroughly  familiar  with  the 'local  conditions  before  enter- 
ing upon  development  work.     It  is  likewise  characteristic  of  the 
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