﻿CRYSTALLINE 
  ROCKS 
  OF 
  THE 
  ALPS. 
  107 
  

  

  abundant. 
  In 
  these, 
  cleavage-foliation 
  dominates, 
  though 
  traces 
  of 
  

   the 
  stratification-foliation 
  can 
  be 
  detected. 
  As 
  a 
  rule, 
  they 
  have 
  

   been 
  almost 
  pulverized, 
  the 
  bulk 
  of 
  the 
  slide 
  consisting 
  of 
  minute 
  chalce- 
  

   donic 
  quartz 
  and 
  minute 
  mica, 
  green 
  or 
  brown, 
  with 
  an 
  occasional 
  

   nest 
  of 
  granular 
  quartz, 
  or 
  a 
  large 
  flake 
  of 
  mica, 
  which 
  seems 
  to 
  

   have 
  escaped 
  destruction. 
  The 
  more 
  micaceous 
  varieties 
  from 
  the 
  

   last 
  locality 
  are 
  so 
  crushed 
  that 
  I 
  have 
  thought 
  it 
  useless 
  to 
  have 
  

   them 
  sliced, 
  as 
  I 
  have 
  no 
  doubt 
  as 
  to 
  their 
  nature. 
  

  

  (c) 
  Three 
  specimens 
  examined. 
  They 
  consist 
  of 
  variable 
  amounts 
  

   of 
  calcite, 
  mica, 
  generally 
  almost 
  or 
  quite 
  colourless, 
  and 
  quartz, 
  

   with 
  a 
  little 
  iron-oxide 
  in 
  grains. 
  All 
  exhibit 
  a 
  cleavage 
  -foliation 
  

   posterior 
  to 
  the 
  crystallization 
  of 
  the 
  constituents 
  ; 
  that 
  on 
  the 
  

   ascent 
  from 
  Windisch-Matrei 
  (p. 
  87) 
  has 
  more 
  quartz 
  and 
  less 
  cal- 
  

   cite 
  than 
  the 
  others 
  ; 
  it 
  is 
  rather 
  discoloured 
  with 
  ferrite 
  and 
  opacite 
  

   and 
  contains 
  several 
  granules 
  of 
  a 
  discoloured 
  brown 
  mineral 
  looking 
  

   not 
  unlike 
  a 
  garnet, 
  but 
  with 
  double 
  refraction 
  — 
  perhaps 
  rutile 
  — 
  

   also, 
  I 
  think, 
  a 
  little 
  zircon. 
  In 
  the 
  specimen 
  associated 
  with 
  the 
  

   green 
  schist 
  from 
  the 
  higher 
  part 
  of 
  the 
  same 
  glen 
  (p. 
  88), 
  calcite 
  and 
  

   dolomite 
  predominate 
  over 
  the 
  other 
  constituents, 
  and 
  there 
  is, 
  I 
  

   think, 
  a 
  little 
  kyanite. 
  In 
  that 
  from 
  the 
  quarry 
  beneath 
  the 
  castle 
  

   at 
  Mittersill 
  calcite 
  predominates, 
  and 
  there 
  are 
  several 
  grains 
  of 
  a 
  

   mineral 
  which 
  is 
  probably 
  epidote. 
  

  

  (d) 
  Five 
  specimens 
  examined. 
  Rather 
  compact 
  white 
  marbles 
  : 
  — 
  

   (a) 
  from 
  the 
  east 
  end 
  of 
  the 
  Castle 
  Rock, 
  Brunecken, 
  (/3) 
  from 
  base 
  of 
  

   Weissenstein, 
  Windisch-Matrei, 
  (y) 
  pale 
  grey 
  finely 
  crystalline 
  mar- 
  

   ble 
  from 
  quarry 
  under 
  castle, 
  Mittersill. 
  Very 
  compact 
  fissile 
  grey 
  

   marble 
  from 
  near 
  Maierhof, 
  Zillerthal, 
  (c)) 
  from 
  near 
  bridge 
  above 
  

   Maierhof, 
  (e) 
  from 
  the 
  Calvarienberg. 
  (a) 
  consits 
  mainly 
  of 
  calcite, 
  

   (/3) 
  and 
  (y) 
  are 
  more 
  strictly 
  dolomite. 
  Besides 
  these 
  carbonates 
  

   there 
  are 
  only 
  a 
  few 
  small 
  flakes 
  of 
  white 
  mica, 
  a 
  few 
  granules 
  of 
  

   quartz 
  or 
  of 
  some 
  colourless 
  silicate, 
  and 
  a 
  little 
  ferrite. 
  (3) 
  contains 
  

   a 
  little 
  more 
  mica, 
  and 
  the 
  calcite 
  is 
  rather 
  " 
  dirty 
  "-looking, 
  (e) 
  has 
  

   still 
  more 
  mica, 
  rather 
  larger 
  and 
  more 
  abundant 
  granules 
  of 
  quartz 
  

   and, 
  perhaps, 
  of 
  a 
  silicate 
  which 
  I 
  cannot 
  identify. 
  

  

  All 
  have 
  been 
  subjected 
  to 
  great 
  pressure. 
  This 
  is 
  indicated 
  by 
  

   the 
  variation 
  in 
  size 
  of 
  the 
  grains 
  of 
  the 
  calcite 
  (or 
  dolomite) 
  and 
  

   the 
  fragment 
  al 
  aspect 
  of 
  the 
  larger, 
  which 
  occur 
  either 
  isolated 
  or 
  

   in 
  groups 
  cemented 
  by 
  a 
  mosaic 
  of 
  the 
  smaller 
  grains. 
  The 
  former 
  

   also 
  have 
  one 
  cleavage 
  strongly 
  developed, 
  and 
  occasionally 
  exhibit 
  

   twinning. 
  Mechanical 
  disturbance 
  is 
  most 
  marked 
  in 
  (0) 
  and 
  (e). 
  

   Now 
  I 
  have 
  always 
  noticed 
  in 
  the 
  Alps 
  that 
  the 
  proverb 
  " 
  noscitur 
  

   a 
  sociis 
  " 
  holds 
  in 
  regard 
  to 
  schists 
  and 
  limestone. 
  If 
  certain 
  macro- 
  

   scopic 
  characters 
  are 
  present 
  in 
  the 
  former, 
  the 
  latter 
  exhibits 
  a 
  

   certain 
  aspect 
  *. 
  But 
  the 
  limestones 
  in 
  the 
  upper 
  part 
  of 
  the 
  Zil- 
  

  

  * 
  I 
  have 
  found 
  this 
  hold 
  good 
  in 
  every 
  region 
  which 
  I 
  have 
  hitherto 
  exa 
  

   mined, 
  though 
  I 
  admit 
  that 
  a 
  limestone 
  is 
  more 
  Hable 
  to 
  mislead 
  than 
  almost 
  

   any 
  other 
  rock, 
  except 
  perhaps 
  a 
  quartzite. 
  Limestones 
  of 
  comparatively 
  recent 
  

   geological 
  age, 
  when 
  altered 
  by 
  igneous 
  rocks, 
  sometimes 
  closely 
  resemble 
  the 
  

   marbles 
  of 
  Archaean 
  age. 
  At 
  the 
  same 
  time 
  I 
  believe, 
  as 
  the 
  result 
  of 
  what 
  I 
  

   have 
  noticed, 
  that 
  further 
  study 
  would 
  reveal 
  differences. 
  

  

  