112 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  260. 
ments,  while  in  other  parts  of  the  same  vein  these  evidences  of  cavity 
filling*  may  be  entirely  absent.     Such  fissure  veins  sometimes  con- 
/  \  / 
\  /     /   /  v- 
\      \     '    N    /    n 
k-   4    /     Is- 
/ 
A^Vo/ 
&. 
^  v  /  s  N  /  -  'w\  'J/2 
v  /  \ 
'v-: 
^  * 
/n'/V/no,/: 
•;0%x-  v 
'**/>/»  I 
/    N  '     V      \ 
N  /  / 
I    I 
/      N 
/  ■        '  i     '      v.         '        ' 
,  N       ^  V    /        s     '  X       N      / 
",  x  /.vi/«  'v'  7T  N '  «V  '/  -  / 
fl 
I 
ilP 
rre 
its 
id 
.1 
In; 
ir 
foci 
k 
Id 
for; 
L 
Scale  of  inches 
3  6  9 
Po  r  p  h  y  r  y 
Siderite        Lead  and  zinc  ore 
Fig  6.— Vertical  section  of  portion  of  the  Sceptre  vein,  showing  reopening  of  Assure  in  prima 
galena  and  blende  ore  filling,  with  subsequent  siderite. 
tract  or  pinch  and  the  vein  becomes  reduced  in  width  to  a  mere  crac 
so  faint  that  miners  are  unable  to  distinguish  it  from  the  joints  < 
the  country  rock. 
