ECKEL.] 
IRON    ORES    OF    NORTHEASTERN    TEXAS. 
Analyses  of  iron  ores. 
353 
Iron  oxide  (Fe203) 
Silicia  (SiO,)  _. 
Alumina  ( A1,03) 
Sulphur  (S)  ---. 
Phosphorus  (P) 
Metallic  iron  (Fe) 
Phosphorus  in  100  parts  iron 
Average 
Texas 
ores. 
Ore  Hill, 
Connecti- 
cut. 
66.  39 
69.71 
14.4? 
9.84 
8.17 
3.  65 
.  088 
.150 
.172 
.196 
46.63 
50.12 
.371 
.  393 
ORIGIN   OF  THE  ORES. 
Most  of  the  ores  of  this  district  occur  in  approximately  horizontal 
Deds,  conformable  to  the  inclosing  sands  and  clays;  but  this  should 
not  be  regarded  as  proof  that  the  ore  deposits  were  formed  at  the 
same  time  as  the  sedimentary  beds  which  now  underlie  and  overlie 
them.  On  the  other  hand,  the  probability  is  that  the  ore  deposits 
were  formed  at  a  much  later  date  than  the  sands  and  clays,  though 
the  source  of  the  iron  may  be  looked  for  in  the  adjacent  sedimentary 
beds. 
The  Claiborne  beds  where  well  exposed  contain  varying  percent- 
ages of  glauconite  and  frequently  considerable  amounts  of  iron 
pyrites.  The  Sabine  or  Lignitic  beds  carry  in  some  horizons  nod- 
jles  and  masses  of  iron  carbonate.  Penrose  has  consequently  held 
;he  view  that  the  brown  hematites  have  been  formed  by  the  decom- 
position of  these  iron-bearing  minerals.  While  there  are  decided 
lifficulties  in  the  way  of  extending  this  explanation  to  cover  all  of 
he  deposits,  it  may  be  accepted  as  sufficiently  satisfactory  for  present 
purposes. 
To  the  miner  the  question  of  origin  of  the  deposits  has  but  one 
)ractical  bearing — i.  e.,  on  the  probability  of  finding  in  depth  richer 
leposits  than  those  now  exposed  at  the  surface  or  in  shallow  dig- 
jpngs.     This  point  fortunately  is  not  involved  in  any  theoretical  dif- 
ferences of  opinion  as  to  the  origin  of  the  Texas  ores.     Under  any 
■probable  hypothesis  it  may  as  well   be   understood  clearly   by   the 
niner  that — 
3    (a)   As  to  size  of  deposit,  there  is  no  probability  that  thicker  de- 
posits will  occur  at  deeper  levels 
(b)  As  to  richness  of  ores,  the  richest  ores  are  likely  to  be  found  at 
4 r  near  the  surface. 
Bull.  260—05  m 23 
