METALLIFEROUS    ORES.  l(.) 
can  determine  the  true  character  of  the  rocks  with  sufficient  certainty  to  render  his  infer- 
ences of  permanent  value. 
Zinc  mines  are  of  rather  exceptional  occurrence  in  Nevada,  and  this  fact  adds  interest 
to  the  report  of  Mr.  Bain,  to  he  found  on  later  pages  of  the  present  volume,  on  the  Potosi 
mine,  in  which  he  finds  certain  analogies  with  the  zinc  deposits  of  the  Mississippi  Valley 
region. 
New  Mexico. — The  Territory  of  New  Mexico  is  rich  in  mineral  deposits,  but  as  yet  no 
great  mining  districts  comparable  to  Butte  and  Cripple  ('reek  have  been  developed  within 
its  boundaries  and  no  detailed  economic  studies  have  hitherto  been  made  (here  by  the 
Survey.  It  has,  however,  a  great  number  of  smaller  mining  districts  of  geological  interesl 
and  of  considerable  economic  importance. 
During  the  past  summer  reconnaissance  examinations  of  all  these  districts  have  been 
made  in  as  much  detail  as  the  want  of  actual  topographic  surveys  will  admit.  This  work 
has  been  under  the  charge  of  Mr.  Waldemar  Lindgren,  who  has  been  assisted  by  Messrs. 
L.  C.  Graton  and  C.  H.  Gordon.  A  preliminary  report  of  the  results  of  their  work  has 
been  prepared  for  this  volume. 
Texas. — The  Franklin  Mountains,  just  north  of  El  Paso,  though  within  the  political 
boundaries  of  Texas,  belong  more  properly  to  the  physiographic  province  of  New  Mexico. 
The  occurrence  of  tin  ores  in  these  mountains  has  long  been  known  and  a  short  description 
of  them  by  Mr.  W.  H.  Weed  was  published  in  Bulletin  No.  178.  During  the  past  summer 
Mr.  G.  B.  Richardson  made  a  reconnaissance  examination  of  the  geology  of  the  entire 
range  and  incidentally  reexamined  the  tin  deposits.  His  report  is  to  be  found  on  later 
pages  of  this  bulletin. 
Utah. — No  systematic  economic  field  work  has  been  done  in  the  State  of  Utah  during 
the  present  season.  A  special  survey  of  the  region  around  Frisco,  in  the  southern  part 
of  the  State,  including  the  Horn  Silver,  Cactus,  and  other  mines,  had  been  planned  and 
the  topographic  basis  for  the  same  was  already  prepared;  but,  owing  to  the  reduction  in 
the  number  of  available  economic  geologists,  there  was  no  one  to  carry  on  the  work  and  it 
has  therefore  been  postponed  until  another  season. 
Mr.  Lindgren  visited  the  State  in  the  interest  of  his  work  on  statistics  of  the  precious 
metals  and  incidentally  made  an  examination  of  the  Annie  Laurie  gold  mine,  in  the  vicinity 
of  Marysvafc,  in  the  southern  part  of  the  State.  His  report,  which  appears  later  in  this 
volume,  will  be  of  interest  as  the  description  of  an  important  gold  mine  in  a  district  of 
whose  geology  little  has  hitherto  been  known. 
