﻿Posnjak 
  and 
  Merwin 
  — 
  Hydrated 
  Ferric 
  Oxides. 
  345 
  

  

  both 
  made 
  up 
  of 
  minute 
  doubly 
  refracting 
  splinters 
  with 
  

   n 
  about 
  2-08. 
  

  

  E. 
  C. 
  701, 
  Shasta 
  County, 
  California, 
  59 
  Analysis 
  No. 
  20. 
  

   — 
  Gossan 
  above 
  ore 
  body. 
  Concentric 
  but 
  not 
  readily 
  

   separable 
  layers 
  of 
  different 
  n, 
  double 
  refraction 
  about 
  

   0-03 
  in 
  some 
  parts, 
  n 
  about 
  2-09 
  (varies 
  between 
  2-13 
  and 
  

   2-06). 
  

  

  E. 
  C. 
  501, 
  Mammoth 
  Mine, 
  Shasta 
  County, 
  California, 
  59 
  

   Analysis 
  No. 
  21. 
  — 
  Gossan 
  surrounding 
  pyrite. 
  Hard- 
  

   ened 
  clot-like 
  masses 
  with 
  only 
  traces 
  of 
  double 
  refrac- 
  

   tion, 
  n 
  = 
  2-00 
  to 
  2-06. 
  Cracks 
  are 
  coated 
  with 
  a 
  thin 
  film 
  

   of 
  red 
  material 
  showing 
  no 
  double 
  refraction 
  and 
  having 
  

   n 
  == 
  2-2 
  to 
  2-3. 
  Out 
  of 
  specimens 
  from 
  about 
  25 
  different 
  

   occurrences 
  of 
  brown 
  ores 
  this 
  is 
  the 
  only 
  one 
  having 
  red 
  

   material 
  that 
  did 
  not 
  resemble 
  turgite. 
  

  

  1255, 
  Holbrook 
  Mine, 
  Bisbee, 
  Arizona, 
  59 
  from 
  the 
  100- 
  

   foot 
  level. 
  — 
  Irregular 
  ropy 
  to 
  platy 
  open 
  structure 
  with 
  

   glazed 
  surfaces 
  resembling 
  the 
  stalactitic 
  limonite 
  of 
  

   Specimen 
  D 
  (see 
  below). 
  Layered 
  structure 
  conspicuous 
  

   under 
  the 
  microscope, 
  double 
  refraction 
  very 
  marked 
  

   (max. 
  0-04), 
  ^ 
  = 
  1-99 
  to 
  2-07. 
  Alternating 
  with 
  the 
  

   brown 
  ore 
  layers 
  are 
  interrupted 
  layers 
  of 
  turgite 
  

   amounting 
  to 
  5 
  to 
  10% 
  of 
  the 
  bulk 
  of 
  the 
  material. 
  

  

  E. 
  C. 
  683, 
  Shasta 
  County, 
  California, 
  59 
  Analysis 
  No. 
  23. 
  

   — 
  A 
  botryoidal 
  mass 
  from 
  a 
  mine 
  dump, 
  separable 
  layers 
  

   having 
  strong 
  double 
  refraction 
  and 
  n 
  varying 
  between 
  

   about 
  2-01 
  and 
  2-06. 
  

  

  Oriskany 
  Mines, 
  Specimen 
  D. 
  60 
  — 
  Stalactitic 
  limonite 
  

   from 
  Botetourt 
  County, 
  Virginia. 
  A 
  porous 
  lace-work 
  of 
  

   small 
  stem-like 
  filaments, 
  irregularly 
  double 
  refracting, 
  

   contains 
  spherules 
  of 
  turgite 
  in 
  interrupted 
  layers, 
  n 
  

   mostly 
  <2-06. 
  

  

  V 
  412, 
  "Wythe 
  County, 
  Virginia. 
  60 
  — 
  Eesidual 
  ore 
  from 
  

   weathering 
  of 
  Shenandoah 
  limestone; 
  contains 
  several 
  

   per 
  cent 
  of 
  red 
  spherulitic 
  granules 
  mostly 
  less 
  than 
  5/x 
  in 
  

   diameter, 
  having 
  refractive 
  index 
  2-4 
  and 
  strong 
  double 
  

   refraction 
  like 
  turgite. 
  

  

  LEPIDOCROCITE. 
  

  

  N. 
  M. 
  81909, 
  Easton, 
  Pennsylvania. 
  — 
  Micaceous, 
  orange 
  

   red, 
  on 
  fibrous 
  goethite 
  ; 
  

   y 
  (Na)= 
  2-51 
  5 
  ; 
  y(Li)== 
  242 
  5 
  ; 
  0(Na)= 
  2-20 
  ; 
  a(Na)= 
  l-93 
  5 
  . 
  

  

  59 
  Analyzed, 
  Table 
  III. 
  

  

  00 
  From 
  a 
  series 
  of 
  selected 
  specimens 
  presented 
  to 
  lis 
  by 
  Professor 
  R. 
  J. 
  

   Holden, 
  Virginia 
  Polytechnic 
  Institute. 
  

  

  