500 
INDEX. 
Page. 
Nevada,  southwestern  part  of,geography  of.        53 
southwestern  part  of,  map  of 54 
minerals  in 56  57 
mining  in 55,57-72 
ore  deposits  of,  character  and  occur- 
rence of 55  57 
railroa  ds  to 53 
rocks  of 55, 100 
work  in 18-19 
zinc  in 166  L69 
New  Era  mine,  V  Dak.,  lignite  of,  analysis 
of 323 
New  Jersey,  magnetite  in 17 
workin 17.21 
New  Mexico,  coal  of 79-80, 204,  240  258 
Colfax  County,  ores  of 82 
copper  in 117   118 
gold  and  silver  in 95,  1  Is 
occurrence  of 79-80 
production  of 93,  117 
smelting  of 90 
gold  of 79-80, 82-80 
(Ira nt  County,  ores  of 83 
lead  of 70-80,84 
map  of 7". 
mineral  deposits  of 79-80 
ore  deposits  of 79-80 
age  of 80-81 
relation  of ,  to  igneous  rocks 85-80 
Otero  County,  ore  deposits  of 83 
physiographic  provinces  of 74  7.") 
placer  gold  of 79,  82 
rocks  of 7  1  79 
Santa  Fe  County,  ores  of 82 
section  <.f 242 
silver  of 79-80,84 
VI  ork  in 19,22,204,206 
zinc  of 7e  80,84 
New  River-Cripple  Creek  disl  riet .  V*a.,  geol- 
ogy  of L90 
iron  ores  of 190-193 
analyses  of 191,192 
origin  of L92  193 
work  in 21 
New  Salem,  N.  Dak.,  lignite  of,  analysis  of.      323 
New  York,  work  in 21 
Newcastle  coal,  character  of 215 
section  of 215 
Newhouse  mine.  Utah,  copper  ores  of 122 
Newhouse  tunnel,  Colo.,  ores  of 39 
Newman  formation,  limestone  of 375 
limestone  of.  analyses  of 375 
Nickel,  bibliography  of 105 
Nickel  Platecoal,  Ada.,  character  of 215 
section  of 215 
Nikolai  greenstone,  copper  in 98 
Nineveh  and  Gordon  oil  sands,  Pa.,  identi- 
fication of 362  366 
Niobrara  formation,  bentonite  in 440 
No  Wood  coal,  Wyo.,  section  of 312 
North  Butte  Copper  Co.,  Mont.,  develop- 
ments by 113-114 
North  Mountain,   Ark.,  clays  on,  analysis 
Of 408,409 
Northport,  Wash.,  iron  ores  near 195 
North  Carolina,  copper  in 115-116 
copper  in,  production  of 93, 115 
Tage. 
North  Dakota,  coal  and  lignite  in 205 
coal  and  lignite  in.    See  also  North  Da- 
kota-Montana lignite  area. 
work  in 22-23 
North  Dakota-Montana  lignite  area,  geol- 
ogy of 310-321 
lignite  of 321-330 
analyses  of 322, 323 
occurrence  of 326-327 
sections  of 324, 325, 327-329 
sections  of 317-320 
North  Dry  Creek,  Wyo.,  coal  near 305 
Northern  Alabama  Mining  Co.,  iron  mine's 
of 178 
Northwestern  Improvement  Co.,  coal  mine 
of 270 
O. 
Oak  Creek  district,  Colo.,  coal  of 228-230 
coal  of,  analyses  of 229-230 
Oak  Spring,  New,  ore  deposits  at 70  71 
o'l'.illon  Creek.  Mont..  Lignite  near,  section 
of 329 
Ohio,  coal  in 200 
work  in 23 
oil.    Set  Petroleum. 
old  Camp.  New.  ore  deposits  of 03-04 
Old  Dominion  Co.,  Ariz.,  production  of..  100-101 
Olive  11  ill,   Kw,  clay  at,  section  of 41  1 
Olivine  in  black  sands,  occurrence  of L52  156 
Orcas  Island,  Wash.,  sandstone  and  shales 
on 378 
Sandstone  and  shales  on,  analysis  of .  ..       378 
Oregon,    black    sands    from,    investigation 
of 159-100 
eopperin 118-119 
gold  and  silver  in 95 
production  of us 
ores,  metalliferous,  investigation  of 14-19 
publications  on 14-10 
Organ  dist  riet,  \.  Mex.,  copper  ores  in  ... .       lis 
Organ  Range,  N.  Mex.,  rocks  of 83 
Oriental  Wash,  Nev.,  ore  deposits  of 04-05 
Oriskany  district,  Va.,  geology  of 185 
iron  ores  of 183-187 
work  in 21 
Oriskany  sandstone,  iron  ores  in 183-187 
iron  ores  in,  analysis  of 187 
bibliography  of 187 
use  of,  for  glass  sand 473 
Orleans  region,  Mass.,  clays  of 437-438 
Oro  Cache  tunnel,  Colo.,  description  of 33 
Ortiz  Mountains,  N.  Mex.,  rocks  of 82-83 
Osmium,  demand  for 150 
Ottawa,  111.,  glass  sand  at 404-465 
glass  sand  at,  analyses  from 450-457 
washings  from,  analysis  of 401 
Ottawa  Silica  Co.,  glass  sand  of 404-465 
Otterson  mine,  Utah,  coal  of 300 
section  of 300 
Owingsville,  Ky.,  iron  ores  at 181-182 
section  at 182 
Owl  Creek,  Wyo.,  coal  near 304-305 
Ozokerite,  character  of 370 
concentration  oi 371 
geologic  relations  of 369-370 
investigation  of 23 
