spencer.] ENCAMPMENT COPPER REGION, WYOMING. 161 
tinuous in depth, but where strong and persistent in outcrop they 
may be expected to continue in depth. This type includes such 
deposits as the Continental in Cow Creek, the Cascade, and the 
Kurtz-Chatterton, in each of which it is anticipated that active devel- 
opment in progress should settle the question of permanence and 
extent of mineralization. 
In the ores of the two properties last named there has been some 
secondary deposition of ore, but the sulphides are regarded as mainly 
primary. 
The second class of copper deposits includes all those where the 
principal copper minerals are rich sulphides, such as chalcocite or 
copper glance, covellite, and bornite, with or without high-grade cop- 
per pyrites. In the surface portion of such deposits large amounts of 
oxide and carbonate ore are found, and they are commonly capped at 
the outcrop with strong gossan. Also the inclosing country rock is 
often to a greater or less extent decomposed. 
Ores of this character are regarded as due to secondary concentra- 
tion or enrichment of ore bodies originally of low grade, through 
processes similar to those which have produced bonanza deposits in 
many other copper camps. 
The secondary deposits of the Encampment district have been thus 
far the only ones supporting productive mines. The ores of the 
Charter Oak, Doaue-Rambler, and Ferris-Haggarty mines are of this 
nature. At the Charter Oak, where the country rock is granite and 
diorite, the deposit appears to have been extremely irregular, but in 
the other mines mentioned the deposits show considerable regularity 
in their occurrence. The ore bodies, inclosed in quartzite of sedi- 
mentary origin, occur in zones of shattered rock which follow the bed- 
ding of the quartzite. Course's of easy circulation for underground 
water have been afforded by local shattering of the rock, which 
doubtless determined the position of original deposition, and later 
allowed of concentration to the form in which the ores are now found. 
In both the Doane-Rambler and the Ferris-Haggarty the secondary 
ores have been opened to a depth of more than 300 feet, though in 
neither instance lias the lowest level of the workings penetrated 
Bore than a short distance below the beds of the gulches adjacent. 
The question of the permanence in depth of these rich secondary 
lores need not be discussed here, since it is a subject which will soon 
be settled in a practical way by the developments now in progress. 
Thus far there seems to be no sufficient reason for supposing that the 
[bottom of the zone of enrichment has been closely approached in 
I either mine. 
From the present study of the region it appears that the future of 
|bhe district must depend very largely upon the discovery of addi- 
tional deposits of the secondary class or type. That such deposits 
Bull. 213—0:3 11 
