﻿Palache 
  — 
  Epidote 
  and 
  Garnet 
  from 
  Idaho. 
  301 
  

  

  its 
  material 
  by 
  the 
  garnet 
  crystal. 
  Outside 
  of 
  the 
  quartz 
  is 
  in 
  

   many 
  instances 
  a 
  similar 
  coating 
  of 
  light 
  green 
  iridescent 
  epi- 
  

   dote 
  and 
  here 
  and 
  there 
  thin 
  plates 
  of 
  hematite 
  are 
  arranged 
  

   between 
  the 
  layers 
  of 
  quartz 
  and 
  epidote. 
  Calcite 
  has 
  also 
  

   formed 
  similar 
  layers 
  in 
  some 
  crystals 
  and 
  where 
  afterwards 
  

   removed 
  by 
  solvents 
  leaves 
  the 
  crystals 
  cavernous. 
  The 
  sur- 
  

   faces 
  of 
  the 
  garnet 
  crystals, 
  whether 
  coated 
  with 
  quartz 
  or 
  epi- 
  

   dote, 
  are 
  smooth 
  and 
  plain 
  and 
  the 
  effect 
  on 
  looking 
  at 
  an 
  

   unbroken 
  crystal 
  is 
  as 
  of 
  pseud 
  omorphs 
  of 
  these 
  two 
  minerals 
  

   after 
  the 
  garnet. 
  

  

  In 
  specimens 
  from 
  the 
  White 
  Monument 
  Mine, 
  crystals 
  of 
  

   cinnamon-brown 
  o-rossularite 
  o^arnet 
  showino^ 
  onlv 
  the 
  form 
  

   p 
  (211) 
  are 
  associated 
  with 
  a 
  little 
  epidote 
  in 
  an 
  impure 
  lime- 
  

   stone. 
  In 
  these 
  garnets 
  layers 
  o£ 
  crystalline 
  calcite 
  are 
  inter- 
  

   polated 
  as 
  in 
  the 
  last 
  described 
  crystals, 
  

   with 
  the 
  difference 
  that 
  here 
  the 
  outer 
  ^ 
  

  

  layer 
  is 
  of 
  garnet 
  substance. 
  

  

  Crystals 
  of 
  brown 
  andradite 
  garnet 
  

   from 
  the 
  Copper 
  Key 
  Mine 
  are 
  notable 
  

   for 
  the 
  etching 
  which 
  they 
  have 
  under- 
  

   gone. 
  The 
  forms 
  originally 
  present 
  

   were" 
  fZ 
  (101) 
  and 
  j9(211) 
  in 
  almost 
  equal 
  

   development 
  and 
  perfectly 
  symmetrical. 
  

   But 
  as 
  shown 
  in 
  tig. 
  3, 
  the 
  crystals 
  have 
  

   been 
  much 
  rounded 
  by 
  deep 
  corrosion 
  of 
  

   all 
  the 
  edges, 
  the 
  solvent 
  action 
  having 
  

  

  been 
  greatest 
  at 
  the 
  ends 
  of 
  the 
  trigonal 
  axes 
  where 
  uneven 
  

   facets 
  have 
  been 
  produced. 
  Shallow 
  rounded 
  grooves 
  replace 
  

   the 
  edges 
  between 
  d 
  and 
  79 
  and 
  a 
  rounding 
  of 
  the 
  angles 
  at 
  the 
  

   ends 
  of 
  the 
  axes 
  gives 
  in 
  some 
  cases 
  an 
  approximation 
  to 
  a 
  cube 
  

   face. 
  The 
  etch 
  facets 
  W'Ould 
  give 
  no 
  measurable 
  reflections 
  

   but 
  their 
  position 
  shows 
  that 
  they 
  are 
  in 
  part 
  trisoctahedrons 
  

   and 
  in 
  part 
  hexoctahedrons. 
  The 
  faces 
  of 
  both 
  d 
  and 
  p 
  still 
  

   retain 
  a 
  brilliant 
  luster, 
  but 
  the 
  former 
  are 
  marked 
  by 
  beauti- 
  

   fully 
  sharp 
  and 
  symmetrical 
  etch 
  pits 
  of 
  rhombohedral 
  outline, 
  

   their 
  edges 
  parallel 
  to 
  the 
  dodecahedral 
  edges 
  of 
  the 
  crystal 
  ; 
  

   and 
  the 
  faces 
  of 
  p 
  are 
  grooved 
  quite 
  deeply 
  parallel 
  to 
  the 
  

   same 
  edges. 
  

  

  A 
  large 
  specimen 
  of 
  vein 
  material 
  from 
  the 
  White 
  Monu- 
  

   ment 
  Mine 
  consists 
  of 
  large 
  cleavage 
  rhombohedrons 
  of 
  calcite, 
  

   each 
  of 
  which 
  serves 
  as 
  a 
  core 
  to 
  a 
  spherical 
  layer 
  of 
  radial 
  

   fibrous 
  calcite. 
  The 
  curved 
  outer 
  surface 
  of 
  these 
  layers 
  is 
  a 
  

   drusy 
  one 
  formed 
  by 
  sharp 
  calcite 
  rhombohedrons, 
  which 
  in 
  its 
  

   turn 
  is 
  coated 
  over 
  with 
  a 
  thin 
  layer 
  of 
  quartz 
  crystals. 
  The 
  

   interspaces 
  between 
  the 
  spheroidal 
  masses 
  are 
  filled 
  with 
  a 
  

   mixture 
  of 
  dead 
  black 
  melaconite 
  and 
  green 
  chrysocolla 
  with 
  a 
  

   small 
  amount 
  of 
  malachite. 
  

  

  