154  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   L906,    PART    T. 
THE    ORE. 
Character. — The  ore  occurs  in  irregular  masses,  bowlders,  pebbles 
sand,  and  as  cementing  material  in  beds  of  conglomerate.  Its  color  h 
dark  brown  and  many  fragments  have  a  black,  varnishlike  luster  on 
botryoidal  surfaces  of  masses  that  show  fibrous  structure  within 
This  ore  has  generally  been  termed  limonite,  but  the  pure  ore  mor 
closely  resembles  gothite  in  composition,  as  is  shown  by  the  following 
two  analyses.  It  is  probably  a  mixture  of  gothite  and  limonite,  if  it 
contains  these  minerals  at  all,  in  the  proporl  ion  of  about  7  to  1. 
Analyses  of  clean  brown  oresfrom  surface,  I  mile  east  of  Russell  i  ill< ." 
Ferric  oxide. . . . 
Siliceous  matter. 
Uumina 
Manganese  oxide. 
I. ini.' 
Magnesia 
phoric  acid . 
Sulphur 
Combined  water. 
Moisl  lire 
84.696 
3.  L59 
.220 
.087 
.  no 
.()2.r> 
.71;:. 
.054 
in   ill 
1.(148 
Total 
Metallic  iron. . . 
Phosphorus. . . . 
Specific  gravity. 
L01.539 
59.287 
.  334 
3.616 
:>14 
81)4 
111 
i88 
407 
045 
700 
085 
206 
$59 
soo 
; 
Mi -I 'alley,  Henry,  Valley  regions  of  Uabama,  pt.  1,  Uabama  Geol.  Survey,  L896,  p.  21:;. 
If  the  ferric  oxide  and  the  combined  water  of  the  above  analyses  he 
averaged  and  then  estimated  on  the  basis  of  ;i  pure  ore,  the  result 
gives  a  content  of  88.36  per  cent  of  ferric  oxide  and  11.53  per  cent  o 
water.  The  theoretical  composition  of  limonite,  according  to  Dana] 
is  ferric  <>.\idc  s.~>.f>  per  cent ,  water  14.4  per  cent;  while  that  of  gothitd 
is  ferric  oxide  89.88  per  cent ,  water  10.12  per  cent. 
In  the  ore  as  mined  the  silica  and  the  alumina  run  much  higher  than 
in  the  above  samples,  owing  1<»  the  presence  of  clay  and  of  chert 
gravel  which  washing  may  fail  to  remove.  Analyses  representing 
the  commercial  ores  of  t  he  district  are  given  below. 
Analyses  of  brown  oresfrom  Russellville,  .1/"..  and  Pinkney,  Tenn. 
Constil  uent. 
1. 
2. 
:;. 
4. 
5. 
0. 
7. 
8. 
Iron  (Fe) 
51.00 
11.  12 
6.  23 
.50.10 
11.  Ml 
6.02 
.-,1.07 
10.60 
5.  01 
47.80 
49.  30 
11.  29 
46.60 
40.80 
Silica  (Si02> 
Alumina  (AI2O31 
. 
Insoluble 
17.00 
L6.90 
'jo.  58 
L6.80 
.45 
.88 
IS.  00 
.  30 
Manganese  CMn) 
.04 
.52 
.ill 
.  59 
.:<7 
.64 
Phosphorus  (P) 
.44 
L,  2, 3,  Monthly  averages  of  ;il!  ores  from  the  Sloss-Sheflield  mines;  1.  .">.  averages  of  ;>  and7cart 
respectively,  from  mines  of  Sheffield  Coal  and  Iron  Company;  »',.  ore  from  Uabama-Virginia  Iron  Ore 
Company;  7,  8,  averages  of  10  and  4  cars,  respectively,  from'  Pinkney,  Tenn. 
