Editorial Commoit. 115 
show several inches or even several feet of ore when followed 
away from the surface, wedge out and finally disappear in bar- 
ren fractures. Deeper workings have not yet discovered any 
such important ore bodies as are frequently found near the 
surface. So far as can be seen the same conditions prevail to- 
day as have existed ever since ore deposition began. There- 
fore there is no reason to suppose that it has yet finished. The 
solution and redeposition of sulphides, probably going on 
now near the surface producing concentration, may be con- 
temporaneous with the primary deposits of leaner sulphides at 
a somewhat deeper zone. 
Ninety-nine per cent, of the entire mineralization of the 
district is said to be along joints. The other one per cent, is 
divided between bedding planes and contact of eruptives Avith 
other eruptives, or with the arkose series. 
The chief joint-systems strike east-northeast, and the east- 
northeast system of veins is overwhelmingly preponderant. 
JMineralization has had no special preferance for joints of any 
particular strike, but there appears to have been a slight select- 
ive tendency for joints of steep dip. The straightest veins 
also are richest, because the straight veins mark a fracture 
zone sufficiently important to control circulation. There has 
been no movement of importance, and the ores have not been 
deposited in cavities or openings, but have replaced the ton- 
alyte or andesyte country rock. 
The chief veins are confined to the igneous rocks and their 
vicinity, and the tonalyte is conspicuous for the number and 
richness of the veins which occur in it and near it. 
Within the tonalyte metallic sulphides in large and small 
segregations are everywhere noticeable. Scarcely a fracture 
crosses the rock, especially where there is water circulation, 
but some concentration of sulphides may be found in it. Often 
away from visible fractures are found bunches of pyrite close- 
ly resembling segregations. 
The ores, however, are not original in the rock, but have 
been formed in joints and joint-zones by replacement of the 
country rock, which shows all the customary products of such 
disintegration and replacement. 
The sulphide ores separate themselves by their location in- 
to two classes, recognized by the miners and called the surface 
ores and the deeper orgs. They are : 
