412 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
This  order  of  superposition  is  usually  maintained  in  this  district.     It  will  thus  be  seen  tb 
there  may  be  four  distinct  varieties  of  clay  present  in  this  noted  seam.     Of  these  the  no  i 
plastic  drab  flint  clay  is  by  far  the  most  important  and  becomes  the  basis  of  refracto  < 
materials  of  the  highest  grade.     The  layer  known  as  "  semihard"  is  on  a  par  with  the  cL 
at  the  horizon  of  the  "  Ferriferous  limestone  "a  to  be  subsequently  described,  though  by  soc 
of  the  clay  workers  the  "  Ferriferous  limestone"  clay,  at  least  at  some  points,  is  considers 
superior.     The  "semihard"  is  a  plastic  or  No.  2  clay  and  is  mixed  w  th  the  flint  clay 
various  proportions,  dependent  on  the  desired  quality  of  the  product.     No.  3  clay  is  a| 
plastic,  but  of  inferior  quality  to  No.  2,  while  that  called  "  pink  eye"  may  be  worked  up  inl 
bricks,  but  the  product  is  off  color.     The  following  analyses  indicate  t  he  very  high  grade 
the  flint  clay  at  this  horizon,  the  percentages  of  silica  and  alumina  approaching  the  then 
retical  values  in  kaolinite. 
Analyses  ofjlint  clay. 
Silica 
Alumina 
I  ion  oxide 
Calcium  oxide 
Magnesium  oxide. 
Phosphoric  acid  . . 
Potash 
Soda 
Water 
50.95 
39.49 
28 
.30 
9.18 
100.20 
48.56 
37.  471 
Trace. 
.112 
Trace. 
.255 
.289 
.283 
b 13. 030 
100.  000 
Trace 
Trace 
14.0! 
99. 
6  Expelled  al  red  heat. 
i.  Sciotoville  fireclay;  X.  w.  Lord,  analyst:  Ohio  Geol.  Survey,  vol.  7,  p.  58. 
2.  From  ridge  between  Grassy  and  Three  Prong  creeks,  Carter*  ounty,Ky.;  sample  collected  by  I*.  N. 
Moore:  Roberl    Peter,  analyst:  Kentucky  Geol.  Survey,  Reporl  on  Eastern  Coal  Field,  vol.  C,  p  10. 
3.  Near  Olive  Bill,  Carter  County;  analysis  furnished  by  Ashland  Fire  15 rick  Company. 
Some  of  the  clay  from  this  horizon  shows  a  rather  high  percentage  of  alumina,  certainly 
higher  than  the  Kaolinite  symbol  calls  for.  Such  clays  are  used  for  kiln  brick  and  have  the 
following  composil  ion:c 
Analyses  of  high-alumina  clays  used  for  kiln  brick. 
1. 
2. 
3. 
4. 
5. 
40.80 
49.00 
n.d. 
n.d. 
n.d. 
n.d. 
ii. 
Silica  (Si02) 
43.38 
10.35 
.85 
.88 
.23 
1  13.41 
44.  52 
40.81 
1.03 
.02 
12.11 
43.05 
•11.  60 
'.Mil) 
.40 
.20 
9. 00 
40.  30 
45.00 
n.d. 
n.d. 
n.d. 
n.d. 
42  71 
Alumina  (A1203) 
38  1 
Iron  oxide  (Fe20:!) 
:;  1 
Lime  (CaO) 
13 
M agnesia  (MgO) 
Carbon  dioxide  (CO;!) 
Water 
99.10 
99.64 
99.85 
85.30 
99.80 
100.1 
1,2.  olive  Hill,  Carter  County,  Ky.;  analyses  from  Stowe-Fuller  Company's  catalogue,  p.  25J. 
3-5.  Hayward,  Carter  County,  Ky.     Ironton  Firebrick  Company. 
6.  Carter  County,  Ky.    Chas.  Taylor's  Sons.     F.  W.  Clarke,  analyst.     Specimen  selected  by  E.  C. 
Eckel. 
o  The  term  "  Ferriferous  limestone"  in  this  report  will  be  employed  in  the  sense  thai  E.  B.  Andrews 
uses  it  in  the  reports  of  the  Ohio  Geological  Survey. 
<■  Analyses  taken  from  Eckel,  E.  C,  Cements,  Limes,  and  Plasters,  1905,  p.  491. 
