CLINTON    ORES    OF    BIRMINGHAM    DISTRICT,  ALABAMA. 
141 
slopes,  is  the  best  in  the  district.  Its  hard  ore  is  also  of  high  grade 
and  hitherto  has  been  for  the  most  part  held  in  reserve,  since  ore  could 
be  produced  from  the  thicker  Big  seam  at  a  lower  cost  per  unit  of  iron. 
The  structure  and  composition  of  the  Big  and  Irondale  seams  is 
shown  in  the  following  series  of  sections,  taken  at  intervals  of  2  to  5 
miles  apart  along  Red  Mountain,  beginning  in  the  northeast  portion 
of  the  mining  district : 
Character  of  Big  and  Irondale  scams  1  mile  northeast  of  Red  (kip,  near  Irondale. 
Thickness. 
Character. 
Sandstone. 
Big  scam: 
Ore,  sandy 
Ore, lean/with  fine  quartz  pebbles. 
Ore,  massive,  cross  bedded,  mined  . 
Ore,  similar  in  appearance  to  above 
but  not  mined  at  present. 
Sandstone,  ferruginous,  lean  ore, 
and  shale. 
Shale 
Sandstone,  very  hard 
"  Gouge,"  calcareous 
Irondale  seam: 
Ore,  mined 
Shale,  hard. 
Ft.  in. 
1 
5 
8 
0 
7 
0 
0 
0 
20 
0 
0-6 
3 
0 
6 
(Metallic  iron,  16-20  per  cent;  insoluble,  40±   per 
I     cent;  lime,  18±  percent. 
/Hard  ore,  averages  metallic  iron,  36  per  cent;  in- 
\    soluble,  26  per  cent;  lime,  20  per  cent. 
I  Percentage  of  iron  grades  down  from  3,5  at  top  to 
less  than  20  at  bottom;  insoluble  rises  to  more 
than  60  per  cent. 
Semihard  ore,  averages  metallic  iron,  37  per  cent; 
insoluble,  29  per  cent;  lime  carbonate,  11.25  per 
cent. 
Character  of  Big  and  Irondale  seams  one-half  mile  south  of  Red  Gap. 
Strata. 
Sandstone,  coarse,  ferruginous. 
Big  seam : 
Ft.  in. 
Ore,    containing    much    silica    in 
coarse  grains  and  fine  pebbles. 
22    0 
Shale                    
1 
Ore,  mined 
7    0 
-Ore,  not  mined 
10    0 
Shale  soft                                             
3    0 
Irondale  seam: 
Ore,  mined 
4    4 
Character. 
'Upper  half,  soft  ore:  Metallic  iron,  22±  per  cent; 
insoluble,  64±  per  cent;  lime,  trace.  Lower 
half,  soft  ore:  Metallic  iron,  32  ±  per  cent;  in- 
{    soluble,  47;h  per  cent;  lime,  trace. 
[Soft  ore:  Metallic  iron,  36±  per  cent;  insoluble, 
[    45±  percent;  lime,  trace. 
[Semihard  ore:  Metallic  iron,  25+  percent;  insolu- 
[    ble,  50±  per  cent;  lime  carbonate,  8.12  per  cent. 
fSoft  ore:  Metallic  iron,  50+.  per  cent;  insoluble, 
\    15+  percent;  lime,  trace. 
Bull.  315-0- 
-10 
