Campbell.]  THE    DEER    CREEK    COAL    FIELD,    ARIZONA.  257 
coke  is  increased  considerably  above  that  which  appears  in  the  coal,  so 
that  instead  of  having  to  deal  with  40  to  43  per  cent  of  ash  it  is  proba- 
ble that  the  coke  will  contain  at  least  50  per  cent,  and  possibly  it  may 
run  to  a  greater  figure. 
The  use  of  such  impure  coke  in  the  copper  smelters  depends  largely 
upon  the  amount  of  silica  contained  in  the  ash.  The  ores  are  gen- 
erally basic,  and  there  is  a  tendency  for  them  to  combine  with  the 
siliceous  lining  of  the  furnace.  It  seems  probable  that  in  case  the 
coke  contains  a  heavy  percentage  of  silica  this  may  combine  with  the 
basic  ores,  thus  relieving  the  siliceous  lining  of  the  furnace  to  a  con- 
siderable extent.  In  order  to  determine  this,  tests  were  made  of  the 
percentage  of  the  silica  in  the  ash,  and  as  shown  in  the  accompanying 
analyses  it  runs  about  50  per  cent. 
As  previously  stated,  it  is  possible  that  this  percentage  of  ash  may 
be  reduced  b}T  washing,  but  this  would  necessitate  the  erection  of  a 
costly  washer  plant  at  the  river,  and  the  gain  may  not  be  sufficient  to 
warrant  the  expenditure.  It  is  recommended,  however,  in  case  these 
coals  are  mined  and  coked  to  experiment  with  washing  and  see  if  the 
percentage  of  foreign  matter  may  not  materially  be  reduced. 
RESUME. 
From  the  foregoing  facts  regarding  the  coal  of  the  Deer  Creek  Basin 
it  seems  safe  to  assume  that  there  are  two  beds  of  workable  thickness 
throughout  the  larger  part  of  this  basin.  The  dimensions  of  the  field 
are  approximately  3  by  10  miles;  its  area  is  about  30  square  miles. 
The  beds  are  thin,  but  from  the  measurements  obtained  it  seems  prob- 
able that  they  range  from  21  to  30  inches  in  thickness,  and  this  is 
within  the  limits  of  a  workable  coal.  The  tonnage  of  the  field,  based 
upon  an  estimate  of  24  inches  of  coal  throughout  a  basin  3  by  10  miles 
in  extent,  is  about  60,000,000  tons.  About  50  per  cent  of  this  may  be 
available,  making  30,050,000  tons  of  coal. 
The  coal  is  fairly  well  disposed  for  mining,  except  where  it  is  sub- 
ject to  local  disturbances  and  where  it  has  been  cut  b}7  igneous  dikes. 
These  disturbances  are  generally  apparent  at  the  surface  and  may  be 
avoided  in  the  location  of  commercial  mines. 
In  a  general  way  the  coal  is  of  two  qualities,  the  first  being  a  hard, 
block  coal,  which  is  fairly  well  adapted  for  transportation  and  for 
commercial  use,  and  also  may  be  manufactured  into  coke.  The  second 
grade  is  a  soft,  badly  crushed  coal,  which  carries  a  heavy  percentage 
of  ash,  and  which,  owing  to  its  peculiar  condition,  probably  can  not 
be  marketed.  It  carries,  however,  a  fairly  large  percentage  of  vola- 
tile matter,  and  it  may  be  utilized  in  one  or  two  ways,  either  by  being 
manufactured  into  gas  and  the  gas  piped  to  the  place  of  consumption, 
or  to  generate  electricity  in  the  field  and  the  power  carried  by  wire  to 
the  place  where  it  is  needed.  By  the  latter  method  only  a  small  per- 
Bull.  225—04 17 
