bain.]  LEAD   AND   ZINC    RESOURCES   OF   UNITED   STATES.  257 
£old,  produces  relatively  little  lead  and  zinc,  though  efforts  are  now 
being  made  to  develop  the  latter. 
Without  entering  upon  an  extended  review  of  the  situation,  it  be- 
comes evident  that  so  far  as  the  West  is  concerned  lead  production  is 
confined  almost  entirely  to  the  States  of  the  Rocky  Mountains  and  the 
Great  Basin.  A  fuller  study  would  show  that  the  big  lead-producing 
samps  are  all  located  in  districts  where  both  igneous  and  sedimen- 
tary rocks  are  involved.  At  Leadville,  Aspen,  and  Park  City  the 
sedimentary  rocks  are  largely  dolomites  and  limestones;  at  Coeiir 
I'Alene  they  are  shales  and  quart zites.  The  igneous  rocks  include 
various  eruptives,  commonly  grouped  under  the  term  "  porphyry." 
Flic  association  of  the  ore  with  igneous  rocks  is  apparently  more 
extensive  than  Avith  sedimentary — witness  the  deposits  of  Clear  Creek 
md  San  Juan  counties,  Colo. — but  it  remains  true  that  the  large  and 
mportant  bodies  are  found  where  both  classes  of  rocks  are  present.  It 
las  already  been  pointed  out  that  the  western  lead  ores  are  almost 
vithout  exception  argentiferous,  and  it  may  be  further  stated  that 
hey  are  usually  intimately  associated  with  a  wide  variety  of  sul- 
fides of  still  other  metals. 
SOFT-LEAD   DEPOSITS. 
Appalachian. — Along  the  eastern  front  of  the  Appalachians,  ex- 
ending  from  Maine  to  Alabama,  and  also  at  certain  localities  in 
vestern  New  York,  there  are  scattered  deposits  which  were  somewhat 
ctively  exploited  up  to  the  middle  of  the  last  century.  The  best 
eneral  description  of  these  was  given  by  Whitney,0  who  wrote 
t  a  time  when  the  work  was  in  the  main  still  open  to  inspection, 
^ery  little  attempt  is  now  being  made  to  work  these  deposits.  A  few 
re  being  developed,  more  on  account  of  the  accompanying  zinc  than 
he  lead,  and  these  will  be  later  considered. 
Wisconsin,  Illinois,  and  Kentucky. — Practically  all  the  soft  lead 
ow  produced  comes  from  the  Mississippi  Valley,  and  nearly  all  from 
lissouri.  The  older  mines  of  Wisconsin,  Iowa,  and  northern  Illi- 
ois  are  worked  mainly  for  zinc.  The  mines  of  southern  Illinois  and 
western  Kentucky  yield  fluorspar,  with  lead  and  zinc  as  by-products, 
nd  the  small  deposits  of  central  Kentucky  are  worked  for  lead  and 
arite. 
In  the  summer  of  1904  an  attempt  was  being  made  to  work  some  of 
le  lead  deposits  near  Georgetown,  Ky.  The  Mutual  Mining  Com- 
any  had  opened  a  small  vein  near  Duval  and  another  near  Kissin- 
er.  The  Lexington  limestone,  which  is  rough  textured,  blue,  and 
onmagnesian,  forms  the  country  rock.  The  veins  seen  were  1  to  2 
feet  wide,  with  sharply  defined  walls,  and  had  courses  respectively 
a  Whitney,  J.  D.,  Metallic  Wealth  of  the  United  States,  1854,  510  pp. 
Bull.  260—05  m 17 
