436  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   L906,   PART    T. 
cementing  materia]  of  the  sandstone  is  less  resistanl  than  the  grain 
themselves;  l>ut  at  times  even  the  sand  grains  show  replacemeJ 
by  brown  ore.  The  result,  on  a  very  small  scale,  is  the  format  ion  of 
ores  like  those  of  the  Rich  Patch,  Lowmoor,  and  Longdale  mines  of 
Virginia. 
Character  of  tin  paint  ore.  The  typical  paint  ore  is  light  blue  in 
color  and  rather  distinctly  laminated.  Kxcept  for  weight  it  tnighl 
readily  be  mistaken  for  a  sandy  shale.  Occasionally  fossils  are  pres- 
ent in  the  ore,  in  which  case  it  looks  still  less  like  an  iron  ore.  drains 
and  riodules  of  iron  pyrite  arc1  scatterd  through  the  ore.  but  not  to 
any  considerable  extent.  The  larger  nodules  of  pyrite  are  picked  out 
before  the  ore  is  sent  to  the  kiln,  and  some  sulphur  is  roasted  oil",  hut 
a  sufficient  aumber  of  small  grains  remain  to  give  the  paint  a  sulphur 
content   <>f  one-half  to   I    per  cent . 
Analysis  ofcrudi  paint  ore,  Lehigh  Gap  district,  Pennsylvania. 
Silica  (Si02) L6.23 
Alumina     U2(  I      5.49 
[ron  oxide    Fe(  I     1 1.50 
Manganese  oxide    MnO) I    L9 
Lime  (.CaO) 3  51 
Magnesia    MgO       L.08 
Sulphur    - '17 
Phosphorus  (P) 02 
Carbon  dioxide  and  organic  matter I 
...  ?24. 35 
Water I 
The  analysis  given  above  was  made  1»\  Mr.  A.  S.  McCreath.0     The 
sample  anal\  zed  is  evident  ly  far  richer  in  iron  t  han  t  he  average  mate 
rial  used  in  the  manufacture  of  paint ,  as  can  be  seen  in  comparing  1  he 
above  analysis  with  the  analyses  of  finished  paint  given  later. 
Methods  of  manufacture.     Two  firms  are  now  operating  in  the  dis 
trict.     Prince's  Manufacturing  Company  is  operating  two  kilns  (one 
west  of  Millport,  the  other  at  Bowman's), and  three  mills,  all  at  Bow- 
man's.    The  Prince  Metallic   Paint  Works  operates  kilns  and  a  mill 
about  half  a  mile  east  <»f  Lehigh  (lap. 
The  kilns  used  in  the  district  are  circular  internally,  wit  h  an  interior 
section  about  5  feet  in  diameter  and  about  infect  inheight.  The  fuel 
used  is  wood,  burned  in  two  furnaces,  the  heat  being  conveyed  to  the 
charge  by  a  checkerwork  of  brick. 
The  ore  i>  charged  at  the  top  of  the  kiln  at  the  rate  of  8  to  K)  long 
tons  a  day.  As  the  kiln  holds  about  16  tons,  the  ore  is  roasted  for 
about  two  days.  One  cord  of  wood  will  roast  8  to  10  tons  of  ore. 
During  the  roasting  the  ore  loses  from  10  to  20  per  cent  in  weight .  and 
the  lumps  assume  a  brownish-yellow  color  on  the  outside.  When 
broken  open  and  pulverized,  the  powder  is  a  deep  brownish  red. 
a  Ann.  Kept.  Pennsylvania  Geol.  survey  for  1886,  pt.  I.  p.  I  K>4. 
