Vol.  49.]  METAMORPHIC  ROCKS  AROUND  THE  SHAP  GRANITE.  361 
In  describing  the  metamorphism  of  the  andesites,  we  have 
remarked  that,  of  the  coloured  silicates,  the  one  most  usually  pro¬ 
duced  is  brown  mica,  hornblende  being  mostly  confined  to  particular 
streaks  and  veins  and  to  the  interior  of  the  vesicles,  where  some 
accumulation  of  calcite  would  favour  the  formation  of  a  lime¬ 
bearing  mineral.  The  basic  lavas,  as  appears  from  Mr.  Garwood's 
figures, 
Andesite, 
West  of  Wasdale  Pike. 
Si02  .  5995  per  cent. 
CaO  .  3’95  per  cent. 
Basic  Lava, 
Low  Fell. 
50‘75  per  cent. 
10’50  per  cent. 
Basic  Asb, 
Low  Fell. 
50‘90  per  cent. 
380  per  cent. 
are  much  richer  in  lime,  and  accordingly  we  find  green  horn¬ 
blende  more  common  than  mica,  in  the  body  of  the  rock  as  well 
as  in  the  contents  of  the  vesicles.  The  ashes  associated  with  the 
basic  lavas,  however,  have  brown  mica  far  more  abundantly  than 
hornblende,  and  the  reason  for  this  is  seen  in  the  low  percentage  of 
lime  which  they  contain. 
The  mode  of  distribution  of  both  hornblende  and  mica  in  the 
metamorphosed  basic  lavas  points  to  these  minerals  having  been 
formed  largely  by  reactions  among  the  weathering-products,  such  as 
the  chloritoid  substances,  calcite,  and  kaolin  ;  but  some  of  the  knots 
and  patches  doubtless  represent  remnants  of  pyroxene  not  destroyed 
by  weathering. 
In  place  of,  or  in  addition  to,  the  hornblende,  we  not  infrequently 
find  a  colourless  pyroxene  with  good  prismatic  cleavage  and  the 
optical  properties  of  an  augite.  The  occurrences  mentioned  as  ex¬ 
ceptional  in  our  account  of  the  andesites  belong  properly  to  the  basic 
group.  The  mineral  seems  to  be  identical  with  the  dominant 
pyroxene  of  the  metamorphosed  Coniston  Limestones.  It  is  usually 
found  in  narrow  veins,  associated  with  epidote  [759],  and  within 
the  larger  vesicles  [1614,  etc.]. 
Epidote  occurs  abundantly,  in  more  or  less  perfect  crystals  and 
in  granular  aggregates.  The  small  grains  show  a  pale  yellow  tint 
with  feeble  pleochroism,  but  in  the  larger  crystals  the  pleochroism, 
changing  from  yellowish  green  to  colourless,  is  quite  vivid.  Zonary 
growth  is  often  indicated  by  the  interior  of  the  crystal  showing 
stronger  absorption  than  the  margin.  The  two  leading  cleavages 
are  usually  evident,  and  when  the  crystals  are  well-bouuded  the 
habit  is  normal  [1614,  etc.].  We  formerly  noted  epidote  in  the 
andesites  of  Little  Saddle  Crag,  some  1350  yards  from  the  granite¬ 
boundary,  but,  as  the  mineral  was  not  found  nearer  the  granite,  we 
doubted  its  connexion  with  the  metamorphism.  In  the  basic 
lavas  there  is  no  room  for  doubt  on  this  point,  and  the  mineral  is 
found  as  an  accompaniment  of  very  considerable  metamorphism, 
though  not  close  to  the  granite-junction.  It  is  characteristically 
found  among  the  contents  of  the  larger  vesicles,  but  occurs  also  in 
certain  veins  and  in  the  general  mass  of  the  rock,  where  it  appears 
to  replace  felspar  [900,  from  Howe  Gill].  The  metamorphic  origin 
of  the  epidote  is  evident  from  its  mode  of  association-  with  the 
Q.  J.G.S.  No.  195.  2  b 
