DISCOVERY  OF  EMERY  IN  CHESTER,  MASS. 
279 
The  principal  bed  of  emery  is  seen  at  the  immediate  base  of 
the  South  Mountain,  where  it  is  four  feet  wide,  and  cuts  through 
the  mountain  near  its  summit,  at  an  angle  of  70°  inclination  or 
dip  to  the  eastward.  Its  course  is  N.  20°  E.,  S.  20°  W.,  and 
its  known  extent  four  miles.  Near  the  summit  of  the  mountain 
the  bed  expands  to  more  than  10  feet  in  width,  and  in  some 
places  is  even  17  feet  wide. 
The  alternations  of  rock  in  two  sections  are  as  follows,  begin- 
ning to  the  eastward : 
1.  a,  Mica  slate ;  5,  15  ft.  soapstone  or  talcose  rock ;  c.  2  ft. 
crystallized  talc  ;  d,  talcose  slate  ;  e,  1  ft.  granular  quartz ;  /, 
chlorite  slate  •  g,  4  ft.  Emery  ;  h,  chloritoid  and  margarite  ;  i9 
magnetic  iron  ore ;  j,  hornblende  rock  highly  crystalline. 
2.  a,  Mica  slate  •  b,  6  ft.  magnetic  iron  ore  ;  c,  talcose  slate ; 
dy  6J  ft.  magnetic  iron  ore ;  e,  chlorite  slate  ;  /,  hornblende 
rock,  crystallized ;  g,  7  ft.  Emery,  chloritoid  and  margarite  ; 
h,  magnetic  iron  ore  ;  %  hornblende  rock. 
The  elevation  of  the  upper  outcrop  of  this  bed  above  the  im- 
mediate base  of  the  mountain  is  750  feet.  There  are  curiou3 
rounded  masses  of  remarkably  pure  emery  three  feet  in  diame- 
ter in  this  bed,  entirely  invested  with  a  coat  of  delicate  rose- 
colored  margarite,  and  a  thick  layer  of  bright  green  chloritoid, 
the  investing  coat  being  from  half  an  inch  to  two  inches  in 
thickness.  It  is  found  extremely  difficult  to  break  up  these 
masses  of  solid  emery,  drilling  holes  in  them  for  blasting  being 
very  slow  and  laborious,  and  no  grip  can  be  had  on  their  rounded 
sides  by  the  sledge.  A  heavy  drop  hammer  will  be  required  to 
break  them  to  pieces — or  they  may  be  cracked  by  fire,  if  heat 
does  not  injure  the  emery. 
A  branch  of  Westfield  river  separates  the  South  from  the 
North  mountain,  a  hill  nearly  750  feet  high,  through  the  summit 
of  which  the  great  .emery  bed  also  cuts.  On  this  hill  the  emery 
is  more  largely  crystalline,  and  less  mixed  with  magnetic  iron 
ore.  It  is  more  like  corundum,  but  still  contains  the  combined 
protoxyd  of  iron,  characteristic  of  true  emery.  Its  specific  gravity 
is  from  3-75  to  3-80,  while  that  from  the  South  mountain  is 
from  4-02  to  4-37;  Naxos  emery  being  from  3-71  to  3-72,  ac- 
cording to  my  trials  of  it,  in  comparison. 
On  the  North  mountain,  three  large  beds  of  rich  magnetic  iron 
