i:k]     ore  deposits  of  silver  peak  quadrangle,  nev.      113 
worth  $46*000;  other  mines  have  yielded  $7,000  or  $8,000.  The  Val- 
calde  Brothers  have  also  taken  out  and  milled  several  thousand  dollars' 
worth  of  ore  from  properties  controlled  by  them. 
The  Drinkwater  group  of  mines,  which  is  the  most  important  part 
of  the  Blair  gold  properties,  and  which  has  produced  practically  all 
of  the  million  dollars'  worth  of  ore,  as  above  stated,  may  be  taken 
as  typical  of  the  gold  veins  which,  though  widespread  and  numerous, 
show  a  wonderful  similarity  of  character.  On  the  surface  two  adjacent 
veins  outcrop,  the  Crowning  Glory  and  the  Drinkwater,  the  former 
the  larger,  the  latter  containing  the  greater  quantity  of  good  ore. 
The  quality  of  the  ore  still  left  standing  (only  the  richer  portions 
having  been  removed  for  milling)  has  been  more  or  less  carefully 
determined  a  number  of  times.  An  exhaustive  and  careful  sampling  by 
Mr.  George  M.  Maynard,  of  New  York,  gave  the  average  assay  value 
of  the  measurable  reserves  of  the  underlying  Crowning  Glory  vein  at 
$5  for  a  tonnage  of  107,370,  making  a  total  value  of  $537,550.  For 
the  measurable  reserves  of  the  Drinkwater  vein  the  average  value  was 
$9.18  for  a  tonnage  of  1,558,  and  a  total  value  of  $12,118;  making 
$579,668  for  the  measurable  reserves  of  both  mines.  Mr.  Maynard 
estimated  the  probable  reserves  of  the  mine  at  nearly  as  much, 
making  a  total  value  of  measurable  and  probable  reserves  of  approxi- 
mately a  million  dollars/'  Since  Mr.  Maynard's  examination,  several 
years  ago,  a  considerable  amount  of  new  development  work  has  been 
done  which  increases  markedly  both  the  measurable  and  the  probable 
reserves. 
Geologically,  the  veins  of  the  Blair  mines  are  interesting.  Properly 
speaking,  they  are  hardly  veins,  but  flattened  lenses  of  quartz  occur- 
ring in  a  definite  zone  100  feet  or  more  in  thickness.  The  lenses 
wedge  out  and  disappear  both  horizontally  and  vertically,  and  their 
place  is  taken  by  overlapping  lenses.  The  wall  rock  is  a  schist,  de- 
rived chiefly  from  the  metamorphism  of  an  original  limy  shale  or  lime- 
stone. Frequently,  also,  the  wall  rock  is  a  very  siliceous  granitic  rock 
(alaskite)  made  up  essentially  of  quartz  and  feldspar.  This  alaskite 
occurs  in  the  schist  in  lenses  similar  to  the  quartz.  There  is,  moreover, 
every  transition  between  the  alaskite  and  the  quartz,  and  the  schist 
has  been,  so  to  speak,  saturated  with  this  siliceous  material,  which  forms 
seams  and  tiny  lenses  in  it.  The  auriferous  quartz  lenses  in  the  mine 
in  many  places  run  laterally  into  quartz-feldspar  rock  (alaskite).  As 
a  rule  the  values  grow  insignificant  with  the  coming  in  of  the  feldspar, 
but  occasionally  high  values  ma}T  still  be  found. 
The  general  conclusion  is  that  here  a  series  of  fissile  shales  and 
thin-bedded  limestones  has  been  invaded  by  a  very  siliceous  granitic 
intrusion  which  has  metamorphosed  the  sediments  to  schists.  The 
quartz  has  plainly  the   same  origin  and    nature  as  the  alaskite,  both 
"  Communicated  by  Mr.  Maynard. 
Bull.  225—04 8 
