272  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  2G0. 
Of  these  the  Silver  Pipe  is  the  most  important,  while  the  outer  or 
west  vein  ranks  next.  The  ore  bodies  are  lenticular  but  very  irregu- 
lar. They  are  rather  large — individual  stopes  25  feet  wide,  100  feet 
high,  and  300  to  800  feet  long,  being  now  open.  The  ore  bodies  repre- 
sent metasomatic  replacements  of  the  limestone.  The  main  ore 
shipped  is  carbonate  of  zinc  carrying  minor  silver  and  copper  values. 
It  goes  to  the  oxide  works  at  Joplin,  Mo.,  and  Mineral  Point,  Wis. 
Mr.  Keyes  estimates  the  output  for  1904  at  about  20.000  tons. 
Minor  western  production. — The  large  majority  of  the  ore  bodies 
of  the  West  which  have  yielded  lead  and  zinc  contain  zinc  in  impor- 
tant amounts.  Coeur  d'Alene  affords  a  striking  exception,  and  Lead] 
ville  an  equally  noteworthy  example.  Apparently  zinc  has  not  been 
produced  in  quantity  outside  of  Colorado  and  Xew  Mexico,  mainly 
because  there  has  not  been  sufficient  demand  for  it.  In  many  of  the 
mine>  of  Utah,  in  particular,  estimates  of  the  amount  of  zinc  avail- 
able for  production  are  now  being  made,  and  it  is  to  be  expected  that 
this  State  will  soon  be  making  regular  shipments.  In  Idaho,  Mon- 
tana, and  other  Western  States  much  the  same  situation  exists,  and 
for  the  present  there  is  no  production  to  record.  In  the  last  two  years 
the  mines  of  British  Columbia  have  shipped  zinc  concentrates 
to  the  Kansas  smelters.  Since,  however,  a  smelter  is  soon  to  be  built 
near  the  mines,  these  imports  are  not  likely  to  continue.  The  close 
similarity  of  the  ores  of  this  district  to  those  found  at  Wood  River, 
Idaho,  and  various  other  western  camps  makes  it  altogether  probable 
that  the  latter,  by  adopting  the  methods  already  applied  in  Canada, 
may  become  important  producers  of  zinc  ore, 
FUTURE    ZINC    PRODUCTION. 
Any  growth  of  the  zinc  industry  in  this  country  is  dependent  upon 
future  increased  domestic '  use  of  zinc  and  upon  the  possibility  of 
acquiring  a  part  of  the  foreign  trade.  As  to  the  first,  it  may  be  con-? 
fidently  affirmed  that  the  local  demand  for  spelter  and  oxide  will  in 
the  future  not  only  increase  with  our  growth  in  population,  but  in 
a  ratio- in  excess  of  that  growth.  Our  per  capita  consumption  of  zinc 
is  less  than  that  of  Europe,  and  we  use  more  expensive  tin  and  copper 
for  many  purposes  for  which  in  other  countries  the  cheaper  metal  is 
substituted.  It  seems  certain  that  in  the  future,  unless  there  should 
be  an  unexpected  decrease  in  the  price  of  copper  and  tin,  zinc  will 
gain  in  use  relatively  to  them,  and  a  continued  discovery  of  new  uses 
i-  also  to  be  anticipated. 
The  foreign  markets  offer  a  seemingly  tempting  field.  The  most 
important  zinc-smelting  centers  of  Europe  import  the  bulk  of  their 
ore,  and  in  recent  year-  there  have  been  many  attempts  to  enter  this 
market  with  American  concentrates.     Experience  so  far  would  seem 
