COPPER, ETC., OF PRINCE WILLIAM SOUND. 81 
feet of the surface. Occasionally small flakes of native copper are found in I he upper parts 
of the veins; this is evidently also a secondary mineral. Oxidation of the iron sulphides 
has given rise to the usual rusty brown capping (iron hat) to the veins, hut this oxidation, 
except along cracks, extends commonl}' only a few inches from the surface. 
The copper veins now being prospected are mainly along shear /.ones. These usually 
occur in the greenstones or in their immediate vicinity. Not uncommonly a shear /one 
agrees closely with the contact between greenstone and a layer of slate or graywacke'. This 
association of the ore deposits with the greenstones is so pronounced that these igneous 
rocks can be regarded as the original sources of the copper. The shear zones vary in width 
from a few inches to several feet — in one case a width of 8 feet being reported. While in a 
few cases there evidently were along the shear zones open cavities which have been Idled 
with metallic sulphides and quartz, the general conditions indicate that the ore minerals 
have replaced the country rock, rather than that they were, deposited in such cavities. 
Most of the prospects show shear zones made up of two rather distinct layers. One is a 
layer of nearly solid sulphides (chalcopyrite, pyrrhotite, and pyrite), or of these sulphides 
mixed with some quartz and country rock; the other layer consists of sheared rock, some- 
times silicified, with disseminated ore minerals. The sulphide layer may be on one wall of 
the shear zone, or it may be near the center of the zone with a layer of disseminated ore on 
either side. This sulphide layer varies considerably in composition in the different pros- 
pects, being in some almost solid pyrrhotite and in others chalcopyrite with little pyrrhotite; 
the variation in composition in any individual sulphide layer is not so marked. In thick- 
ness these sulphide layers vary from an inch to, in one case, 8 feet; and any given layer varies 
in width along both the strike and the dip. Some of the sulphide layers pinch out entirely 
along the strike and then reappear; thus bodies of ore of lens-shaped cross section occur 
whose length is several times their greatest thickness. These lenses may also pitch along 
the direction of the strike. Individual veins have been traced continuously for half a mile 
or more, and further prospecting will undoubtedly show T that some of them can be followed 
for several miles. In view of the irregularities of the surface and the absence of detailed 
maps it is difficult to trace individual shear zones except in the few cases where outcrops are 
frequent. The strikes of the veins vary considerably, but frequently agree rather closely 
with that of the country rock. The dips of the veins are commonly high, usually between 
60° and 90°. 
In addition to the shear zones there are some sharply defined veins of small size, and on 
Knight Island prospecting has been done in a rather massive greenstone which contains dis- 
seminated chalcopyrite and pyrrhotite. The two producing mines of the district are in 
deposits which differ somewhat from the simple shear zones above described. 
The ore deposits now known occur, with very few exceptions, in the rocks of the Orca 
series. 
COPPER MINES. 
The Gladhaugh mine is situated at Ellamar on Virgin Bay, on the northeast shore of 
Prince William Sound. (See fig. 4, p. 79.) The ore body outcrops on the beach between 
low and high tide marks. It was staked in 1897. During the summer of 1905 this mine 
shipped about 1,500 tons of copper ore per month. The 100-, 200-, 300-, and 400-fool levels 
of the mine have been opened up, and work was progressing on the 500-foot level in Sep- 
tember, 1905. Since this date it is reported that the ore body has been encountered on this 
lowest level. The ore on the 200-foot level has a roughly lens-shaped cross section with a 
length of 190 feet and an extreme width of 80 feet. The direction of the long axis is ap- 
proximately N. 35° W. The dip of the walls varies from 80° to 90° NE. and t here is a pitch 
of the ore body of about 35° E. The ore body consists of chalcopyrite, pyrite, pyrrhot he. 
and country rock. Frequently the rock is lacking and then the ore body is practically 
solid sulphides, with the chalcopynite in marked amount. The best ore, i. c., that in which 
the proportion of chalcopyrite is highest, is in general confined to a poorly defined ore 
