﻿390 
  JOURNAIv 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  17 
  

  

  America, 
  made 
  by 
  me 
  and 
  others, 
  especially 
  in 
  its 
  high 
  silica, 
  rather 
  

   high 
  magnesia 
  and 
  lime, 
  and 
  low 
  soda. 
  In 
  most 
  respects 
  it 
  is 
  inter- 
  

   mediate 
  between 
  the 
  jade 
  of 
  the 
  Tuxtla 
  statuette 
  and 
  that 
  from 
  

   Chichen 
  Itza 
  shown 
  above. 
  The 
  former 
  is 
  composed 
  entirely 
  of 
  

   diopside-jadeite 
  (the 
  two 
  being 
  present 
  in 
  about 
  equal 
  amounts), 
  

   while 
  the 
  latter 
  is 
  about 
  two-thirds 
  albite 
  and 
  one-third 
  diopside- 
  

   jadeite. 
  

  

  The 
  relations 
  are 
  perhaps 
  better 
  shown 
  when 
  the 
  analyses 
  are 
  

   recalculated 
  into 
  terms 
  of 
  their 
  mineral 
  molecules. 
  

  

  TABLE 
  I. 
  — 
  Analyses 
  of 
  Jades 
  from 
  Central 
  America 
  

  

  Si02 
  

  

  AI2O3 
  

  

  Fe203 
  

  

  FeO 
  

  

  MgO 
  

  

  CaO 
  

  

  NazO 
  

  

  K2O 
  

  

  H2O 
  

  

  Ti02 
  

  

  Cr203 
  

  

  MnO 
  

  

  1 
  

   62.64 
  

   14.92 
  

   0.60 
  

   1.25 
  

   4.31 
  

   5.92 
  

   8.78 
  

   0.23 
  

   1.27 
  

   none 
  

   none 
  

   none 
  

  

  99.92 
  

  

  99.59 
  

  

  3 
  

  

  64.64 
  

  

  18.83 
  

  

  0.46 
  

  

  0.49 
  

  

  1.87 
  

  

  2.62 
  

  

  11.25 
  

  

  0.23 
  

  

  0.16 
  

  

  none 
  

  

  0.07 
  

  

  none 
  

  

  100.62 
  

  

  1. 
  Jade 
  Copan 
  pebble. 
  Washington 
  analyst. 
  

  

  2. 
  Diopside-jadeite, 
  Tuxtla 
  statuette, 
  Washington 
  analyst. 
  H. 
  S. 
  Washington, 
  Proc. 
  

   U. 
  S. 
  Nat. 
  Mus. 
  60: 
  Art. 
  14. 
  1922. 
  

  

  3. 
  Jade 
  bead, 
  gray-green. 
  Chichen 
  Itza, 
  Yucatan. 
  Washington 
  analyst. 
  

  

  Table 
  2. 
  — 
  Analyses 
  of 
  Central 
  American 
  Jades 
  in 
  Terms 
  of 
  Mineral 
  Molecules 
  

  

  Here 
  we 
  note 
  the 
  extremely 
  pyroxenic 
  character 
  of 
  the 
  Tuxtla 
  

   jade 
  (2), 
  while 
  the 
  Copan 
  (1) 
  and 
  Chichen 
  Itza 
  (3) 
  jades 
  contain 
  

   about 
  the 
  same 
  proportions 
  of 
  albite 
  and 
  pyroxene. 
  In 
  the 
  Copan 
  

   jade, 
  however, 
  there 
  is 
  about 
  two 
  and 
  a 
  half 
  times 
  as 
  much 
  diopside 
  

   as 
  jadeite, 
  while 
  in 
  that 
  from 
  Chichen 
  Itza 
  the 
  relation 
  is 
  almost 
  

  

  