GRAPHITE    IN    MAINE.  483 
of  the  schist  with  the  pegmatite  bodies.  Exploration  of  the  schist  away  from  these  contacts 
in  the  hope  of  discovery  of  other  and  larger  deposits  would  be  unwarranted.  The  amount  of 
graphite  exposed  along  these  contacts  would  vary  much  from  place  to  place,  but  judging 
from  the  exposures  seen  in  October,  1905,  as  well  as  the  nature  of  this  deposit,  the  tonnage 
of  even  8  per  cent  product  would  be  too  small  to  form  the  basis  of  profitable  mining.  Any 
doubt  as  to  the  truth  of  this  statement  regarding  quantity  is  at  once  set  aside,  if  the  difficull  ies 
of  milling  the  rock  are  considered.  It  is  difficult  to  conceive  of  a  practicable  process  by 
which  this  graphite  percentage  of  8.5  would  be  increased  to  20.  Even  if  a  product  of  that 
grade  could  be  secured,  it  would  hardly  be  marketable  in  competition  with  higher  grade 
graphite.  The  content  of  graphite  would  be  too  small  to  give  the  material  much  value 
even  for  the  manufacture  of  paint  or  stove  polish,  while  the  impurities  present  would  unfit  it 
for  other  purposes. 
The  graphite  at  Yarmouth  differs  greatly  from  that  already  described.  The  size  of  the 
fla  kes  is  larger  and  the  proportion  of  graphite  present  more  constant.  The  smaller  individual 
flakes  vary  from  one-half  to  1  mm.  in  diameter,  with  larger  flakes  often  2  mm.  or  more  in 
diameter.  If  this  rock  were  crushed  and  sized  on  a  60-mesh  screen  it  seems  probable  that 
the  material  would  be  in  good  condition  for  a  mechanical  separation  of  the  associated  min- 
erals. The  small  amounts  of  mica  noted  might  make  it  difficult  to  secure  a  perfectly  pure 
product.  The  fineness  of  this  clean  graphite  would  affect  its  value,  but  a  coarser  and  more 
valuable  product  might  be  secured  by  improved  methods. 
The  percentage  of  graphite  in  the  Yarmouth  pegmatite  is  given  above  as  9.  The  sample 
analyzed  was  collected  as  representative  of  the  whole  dike  so  far  as  seen  in  the  few  expos- 
ures. If  this  truly  represents  the  proportion  of  graphite  present,  it  indicates  roughly  the 
amount  of  rock  that  must  be  quarried  to  secure  a  ton  of  commercial  product.  This 
becomes  an  important  factor  in  the  question  of  practicability  of  utilizing  this  deposit,  espe- 
cially since  the  dike  is  so  narrow  that  the  amount  of  dead  work  would  be  proportionably 
large.  On  the  other  hand,  the  proximity  to  the  seaboard  is  one  feature  favoring  the  working 
of  the  Yarmouth  deposit.  All  these  details  need  to  be  carefully  considered  in  estimating 
the  cost  of  mining  and  milling  the  graphitic  product.  Thus,  while  flake  graphite  is  present 
in  good  amount  in  the  Yarmouth  dike,  the  practical  value  of  the  deposit  is  somewhat  in 
uoubt  in  view  of  the  size  of  the  dike  in  which  this  mineral  occurs.  It  is  probable  that  this 
dike  is  persistent  for  a  considerable  distance  horizontally  and  to  whatever  depth  it  could  be 
profitably  followed,  and  there  seems  no  reason  to  expect  the  content  of  graphite  to  change 
essentially. 
Other  occurrences  of  graphite  are  reported  in  Maine,  and  are  believed  to  belong  to  one  or 
the  other  of  the  types  described  above.  Their  economic  utilization  is  desirable,  yet  it  involves 
questions,  similar  to  those  suggested  in  this  article,  which  deserve  careful  consideration. 
Thorough  investigation  will  be  necessary  in  each  case  to  determine  the  actual  value  of  the 
deposit. 
