weed]  NOTES    ON    THE    COPPER    MINES    OE    VERMONT.  193 
paorphic  minerals.  In  the  main  part  of  the  ore  body  it  consists  of 
very  massive  pyrrhotite,  with  small  amounts  of  quartz,  etc. 
The  copper  appears  to  be  confined  to  the  chalcopyrite,  and  though 
it  is  asserted  by  some  observers  that  the  pyrrhotite  of  the  Elizabeth 
mine  contains  some  copper,  an  examination  of  thin  sections  indicates 
that  the  copper  is  held  in  minute  grains  of  chalcopyrite. 
The  chemical  composition  of  the  ores  is  shown  by  the  following 
average  of  a  large  number  of  chemical  analyses  made  of  ore  from  the 
Elizabeth  mine.  It  should,  however,  be  understood  that  this  ore  con- 
tains less  silica  than  the  ores  of  other  localities. 
Average  composition  of  copper  ore  from  the  Elizabeth  mine,  South  Strafford,   Vt. 
Per  cent. 
Copper 3.  25 
(Or  between  1  and  4  per  cent.) 
Iron 35.  60 
Silica 27.  00 
Lime 1.  55 
Sulphur 19.18 
Magnesia 0.  82 
Alumina 7.  76 
Zinc 1.07 
96.23 
Gold Trace  to  0. 02  oz.  per  ton. 
Silver 0.20  oz.  per  ton. 
The  ore  when  cobbed  to  5  per  cent  gave:  Iron  30  per  cent,  silica  21.4 
per  cent.  The  Ely  ore  carries  about  15  per  cent  more  silica,  and  the 
Corinth  mines  are  of  intermediate  character.  The  relative  amounts 
of  silver  and  copper  in  the  ore  are  about  0.10  ounce  of  silver  to  each 
per  cent  of  copper.  Gold  is  commonly  present  in  mere  traces,  but, 
though  the  values  sometimes  run  up  to  $1.20  per  ton  of  ore,  they  are 
spotty  and  seem  to  bear  no  relation  to  the  percentage  of  copper.  The 
blister  copper  produced  at  the  Ely  smelter  in  1899  gave  13  ounces  silver 
and  $2  in  gold  per  ton,  which  is  lower  in  silver  than  the  above. 
Unlike  the  Elizabeth  ores  the  product  of  the  Copperfield  mine  shows 
a  very  uneven  distribution  of  the  silver  values  as  shown  by  the  fol- 
lowing assays  of  selected  ores: 
Assays  of  copper  ores  from  the  Copperfield  or  Ely  mine,  West  Fairlee,  Vt. 
Sample  No. 
Silver. 
Copper. 
1 
Ounces. 
1.28 
.44 
.62 
.76 
Ounces. 
23.15 
2 
13.25 
3                                           
19.75 
Eureka  4..                     -- 
19.  65 
The  normal  ores  carry  an  average  of  0.5  ounce  of  silver  per  ton. 
Bull.  225—04 13 
