﻿132 
  T. 
  H. 
  Lee 
  — 
  Two 
  New 
  Zircon 
  Minerals. 
  

  

  It 
  is 
  clear 
  that 
  in 
  the 
  process 
  of 
  decomposition 
  the 
  

   euxenite 
  has 
  lost 
  a 
  part 
  of 
  the 
  rare 
  earths, 
  oxide 
  of 
  

   uranium, 
  and 
  titanic 
  acid, 
  bnt 
  little 
  or 
  none 
  of 
  the 
  earthy 
  

   acids 
  (Cb 
  2 
  5 
  -Ta 
  2 
  5 
  ). 
  

  

  Considering 
  again 
  the 
  molecular 
  relations 
  of 
  these 
  

   two 
  minerals, 
  it 
  is 
  to 
  be 
  noted 
  that 
  in 
  the 
  relation 
  

   between 
  zirconia 
  and 
  silica 
  in 
  the 
  first 
  case, 
  and 
  between 
  

   the 
  zirconia 
  and 
  titanic 
  acid 
  in 
  the 
  second, 
  there 
  is 
  a 
  

   small 
  excess 
  of 
  acid 
  in 
  each. 
  

  

  In 
  orvillite 
  for 
  example, 
  in 
  place 
  of 
  the 
  relation 
  

   4Zr0 
  2 
  .0 
  2 
  : 
  3Si0 
  2 
  it 
  is 
  3-96 
  Zr0 
  2 
  : 
  3Si0 
  2 
  . 
  

  

  In 
  oliveiraite, 
  in 
  place 
  of 
  3Zr0 
  2 
  : 
  lTi0 
  2 
  , 
  we 
  have 
  

   3Zr0 
  2 
  : 
  2-16Ti0 
  2 
  . 
  

  

  This 
  curious 
  fact 
  is 
  notable 
  in 
  the 
  minerals 
  of 
  zir- 
  

   conium. 
  In 
  Dana's 
  great 
  work 
  there 
  are 
  given 
  twelve 
  

   analyses 
  of 
  zirconite, 
  and 
  in 
  all 
  of 
  them 
  the 
  zirconia 
  is 
  

   low 
  in 
  relation 
  to 
  the 
  silica, 
  the- 
  mean 
  being 
  Zr0 
  2 
  : 
  Si0 
  2 
  = 
  

   1 
  : 
  1-024, 
  in 
  place 
  of 
  Zr0 
  2 
  : 
  Si0 
  2 
  — 
  1:1, 
  or 
  an 
  excess 
  of 
  

   silica 
  of 
  0-024 
  molecule 
  for 
  molecule. 
  

  

  In 
  the 
  case 
  of 
  orvillite 
  this 
  excess 
  is 
  0-01 
  molecule 
  for 
  

   molecule, 
  and 
  in 
  that 
  of 
  oliveiraite 
  0-08 
  molecule 
  for 
  

   molecule. 
  

  

  