﻿Geology 
  and 
  Mineralogy. 
  145 
  

  

  plant 
  and 
  locomotive 
  engineers; 
  by 
  J. 
  M. 
  Wadsworth. 
  Pp. 
  

   86 
  ; 
  4 
  pis., 
  17 
  figs. 
  

  

  6. 
  Gems 
  and 
  Precious 
  Stones. 
  — 
  Two 
  chapters 
  on 
  this 
  sub- 
  

   ject 
  by 
  W. 
  T. 
  Schaller 
  from 
  the 
  volumes 
  on 
  U. 
  S. 
  Mineral 
  

   Resources 
  have 
  been 
  issued 
  during 
  the 
  past 
  year. 
  From 
  the 
  

   report 
  for 
  1916 
  may 
  be 
  noted 
  the 
  fact 
  of 
  a 
  small 
  production 
  of 
  

   diamonds 
  in 
  Arkansas 
  • 
  it 
  is 
  added 
  that 
  a 
  report 
  on 
  this 
  diamond- 
  

   bearing 
  area 
  is 
  in 
  preparation 
  by 
  H. 
  D. 
  Miser 
  of 
  the 
  XJ. 
  S. 
  

   Geological 
  Survey. 
  Isolated 
  diamonds 
  have 
  been 
  found 
  in 
  

   Cherokee 
  Flat, 
  Butte 
  Co., 
  Cal., 
  and 
  Brown 
  Co., 
  Indiana. 
  The 
  

   last 
  named 
  specimen 
  had 
  a 
  weight 
  of 
  1-48 
  carats. 
  New 
  occur- 
  

   rences 
  of 
  dumortierif 
  e 
  in 
  New 
  Mexico 
  and 
  Nevada 
  are 
  also 
  noted. 
  

  

  The 
  chapter 
  from 
  the 
  report 
  for 
  1917 
  is 
  especially 
  valuable 
  

   as 
  giving 
  a 
  minute 
  list 
  of 
  gem 
  names 
  covering 
  many 
  pages. 
  

  

  7. 
  The 
  Adirondack 
  Graphite 
  Deposits; 
  by 
  Harold 
  L. 
  Alling. 
  

   Bull. 
  199, 
  New 
  York 
  State 
  Museum. 
  Pp. 
  150 
  ; 
  25 
  figs.— 
  This 
  is 
  

   an 
  interesting 
  and 
  valuable 
  contribution 
  to 
  the 
  literature 
  con- 
  

   cerning 
  our 
  useful 
  minerals. 
  It 
  describes 
  in 
  detail 
  the 
  geo- 
  

   logical 
  structure 
  of 
  the 
  graphite 
  deposits 
  in 
  the 
  Adirondack 
  

   region 
  and 
  gives 
  many 
  maps 
  and 
  sections 
  of 
  particular 
  areas. 
  

   There 
  are 
  chapters 
  also 
  on 
  the 
  uses 
  and 
  origin 
  of 
  the 
  mineral. 
  

  

  The 
  Adirondack 
  deposits 
  can 
  be 
  roughly 
  divided 
  into 
  two 
  

   areas, 
  the 
  northern 
  and 
  southern 
  which 
  show 
  distinct 
  differ- 
  

   ences 
  in 
  character. 
  The 
  deposits 
  of 
  the 
  northern 
  area 
  are 
  mostly 
  

   of 
  the 
  contact 
  type, 
  lying 
  in 
  the 
  zone 
  between 
  an 
  igneous 
  and 
  a 
  

   metamorphosed 
  sedimentary 
  rock. 
  The 
  rocks 
  most 
  commonly 
  

   so 
  grouped 
  are 
  pegmatite 
  and 
  limestone, 
  although 
  graphite 
  is 
  

   also 
  found 
  with 
  various 
  other 
  combinations. 
  The 
  contact 
  deposits 
  

   in 
  general 
  are 
  too 
  uncertain, 
  too 
  irregular 
  and 
  limited 
  in 
  extent 
  

   to 
  pay 
  for 
  mining. 
  The 
  graphite 
  in 
  this 
  type 
  of 
  deposit 
  is 
  

   believed 
  to 
  be 
  of 
  an 
  inorganic 
  origin, 
  probably 
  derived 
  from 
  

   carbon 
  monoxide 
  or 
  carbon 
  dioxide 
  gases. 
  

  

  The 
  southern 
  area 
  is 
  the 
  region 
  of 
  productive 
  mines. 
  The 
  

   deposits 
  here 
  are 
  in 
  the 
  form 
  of 
  beds 
  with 
  strong 
  evidence 
  that 
  

   the 
  graphite 
  is 
  a 
  definite 
  constituent 
  of 
  the 
  rock 
  strata 
  in 
  which 
  

   it 
  lies. 
  The 
  origin 
  in 
  this 
  type 
  of 
  deposit 
  is 
  considered 
  to 
  be 
  

   organic 
  in 
  its 
  nature. 
  There 
  are 
  four 
  different 
  rock 
  types 
  in 
  

   which 
  the 
  graphite 
  is 
  found, 
  namely: 
  1, 
  a 
  quartz 
  schist 
  with 
  

   5 
  to 
  7 
  per 
  cent 
  graphite 
  ; 
  2, 
  a 
  feldspar-quartz 
  schist 
  with 
  6 
  per 
  

   cent 
  graphite 
  and 
  10 
  per 
  cent 
  micaceous 
  minerals; 
  3, 
  a 
  meta- 
  

   morphosed 
  variety 
  of 
  the 
  quartz 
  schist 
  in 
  which 
  pyroxenes 
  and 
  

   tourmaline 
  have 
  developed 
  and 
  in 
  which 
  the 
  graphite 
  has 
  been 
  

   concentrated 
  in 
  certain 
  layers 
  ; 
  4, 
  a 
  meta-arkose 
  composed 
  almost 
  

   entirely 
  of 
  potash 
  feldspar. 
  w. 
  e. 
  f. 
  

  

  8. 
  Genesis 
  of 
  the 
  Zinc 
  Ores 
  of 
  the 
  Edwards 
  District, 
  St. 
  Laiv- 
  

   rence 
  County, 
  N. 
  Y.; 
  by 
  C. 
  H. 
  Smyth, 
  Jr., 
  Bull. 
  201, 
  New 
  York 
  

   State 
  Museum, 
  1918. 
  Pp. 
  39, 
  12 
  pis.— 
  The 
  ore 
  deposits 
  of 
  the 
  

   Edwards 
  district 
  occur 
  in 
  a 
  belt 
  of 
  Precambrian 
  rocks 
  made 
  up 
  

   chiefly 
  of 
  a 
  thoroughly 
  metamorphosed 
  limestone. 
  These 
  rocks 
  

  

  