KAOLINS    AND    FIRE    CLAYS    OF    CENTRAL    GEORGIA.  309 
Physical  tests a  show  that  the  clay  requires  2 1  per  cent  of  water  to 
develop  a  plastic  mass,  and  that  when  made  into  air-dried  briquettes 
it  has  a  tensile  strength  of  50  to  55  pounds  per  square  inch,  and  air 
shrinkage  of  5  per  cent.  The  clay  when  burned  to  cone  8,  or  about 
2,354°  F.,  was  pure  white,  without  trace  of  a  yellowish  tint.  At 
3,100°  F.  the  material  showed  no  signs  of  fusing. 
At  the  pit  of  I.  Mandle  &  Co.,  2  miles  south  of  Dry  Branch,  only  10 
feet  of  white  clay  is  exposed,  but  the  bed  is  probably  somewhat  thicker 
and  is  of  large  extent  areally.  The  clay  here  is  white,  semihard,  and 
very  free  from  quartz  grains.  It  is  too  hard  for  a  No.  1  paper  clay, 
but  is  very  pure  and  is  sold  crude  and  in  bulk  almost  entirely  for 
pottery  use. 
The  clay  beds  at  the  above  four  localities  are  in  the  same  geological 
position,  namely,  at  the  top  of  the  Tuscaloosa,  and  in  contact  with 
Eocene  sand  and  clay.  They  are  parts  of  one  persistent  clay  forma- 
tion that  ranges  in  thickness  from  10  to  35  feet.  The  strata  in  this 
region  are  nearly  horizontal,  having  only  a  very  slight  dip  southward. 
The  amount  of  overburden  of  the  clay  beds  may  be  estimated  from 
surface  levels. 
MCINTYRE    AND    GORDON. 
In  the  vicinity  of  Mclntyre  and  Gordon,  on  the  Central  of  Georgia 
Railway,  22  and  30  miles,  respectively,  east  of  Macon,  there  are  exten- 
sive beds  of  fire  clays  and  some  pottery  kaolins.  The  fire  clays  lie  at 
the  base  of  Tertiary  ridges  and  are  exposed  wherever  the  small 
streams  have  cut  through  the  Tertiary  clays  and  sands  that  form  the 
surface  rock.  The  clays  are  usually  white1  in  color  and  range  in  hard- 
ness from  soft,  semihard  and  Spunky"  to  very  hard.  They  are  both 
plastic  and  nonplastic  and  show  fusing  points  ranging  from  Seger 
cones  28  to  36  (3074°  F.  to  3362°  F.).  The  soft  clays  contain  more 
iron  than  the  Dry  Branch  kaolins  and  are  in  places  mottled  red,  yel- 
low, and  purple  by  iron  oxide.  Some  of  the  fire  clays  are  very  hard 
and  consist  of  about  equal  parts  of  quartz  sand  and  kaolin,  the  kaolin 
forming  the  cementing  material.  Throughout  this  region  there  are 
peculiar  "punky,"  white,  pitted  clays,  which  have  the  property  of 
hardening  slightly  upon  exposure.  This  clay  is  sawed  from  quarries 
and  used  locally  for  building  chimneys  and  foundations.  It  pos- 
sesses little  or  no  plasticity,  but  is  highly  refractory  and  would  be 
especially  useful  when  finely  ground  for  making  fire  brick.  The  clay 
beds  of  this  region  vary  in  thickness  from  10  to  30  feet  and  are  entirely 
undeveloped. 
a  Tests  made  by  H.  Ries  for  the  Georgia  Kaolin  Company. 
