60 ALASKAN MINERAL RESOURCES IN 1904. [bull. 259. 
The explorations and developments aggregate 1,500 feet of shaft sink- 
ing, crosscutting and drifting. On the surface, besides the shaft 
house, is a well-built 20-stamp mill, a compresser plant run by water- 
power, and other mine improvements. Work on this property has 
been suspended since the early part of 1904. 
At the head of Duncan Canal are several copper prospects and gold- 
bearing ledges which are at present receiving considerable attention. 
Here also the country rock is greenstone-schist which has been 
intruded by wide dikes of fine-grained diorite. 
Near the north end of the east arm, on the west slope of the moun- 
tain range, 2 miles from the shore, is the Portage Mountain group of 
claims. Here four well-defined ledges striking in a northeast direc- 
tion have been prospected, and it is proposed to drive a crosscut tunnel 
during the winter of 1904-5 which will undercut the entire system. 
The ores are in the main chalcopyrite and pyrite, often accompanied 
by magnetite and pyrrhotite. 
On the west side of the east arm is another group of locations on 
what is supposed to be a continuation of one of the above-mentioned 
ledges. This property is also to be developed this coming year. 
A third prospect is located 2 miles up the creek, entering the north 
side of the west arm of the canal. At this point the ore body is a 
mineralized limestone which occurs in the greenstone-schist series, and 
is in places traversed by seams along which a concentration of the 
mineral has been effected. The ore is pyrite with some galena, from 
which favorable assay returns are reported. Explorations on this 
property have just been started and the extent of the ore body has not; 
been determined. 
A somewhat novel feature is the presence of gold-bearing quartz 
ledges in the intrusive granite belt on Woronkofski Island. These 
are situated on the north end of the island, on a point called the Ele- 
phant's Nose, and have been located as the Exchange Group of claims. 
The quartz ledges are later than the granite, and in them are many 
inclusions of granite masses, altered, and more or less impregnated 
with mineral. Two ledges averaging 12 feet in width have been 
opened by two tunnels and open cuts, and from these exposures fair 
gold assays are reported. These properties have remained idle for 
the last few years. 
Glacier basin. — Glacier basin is a glacially eroded depression at an 
elevation of 2,000 feet on the mainland, 14 miles due east of Wrangell and 
8 miles from tide water. The mineral deposits are all found in the 
schist series adjacent to the Coast Range intrusive belt to the east. 
Their general trend is northwest and the dip northeast. Narrow 
granitic belts and porphyritic dikes, probably offshoots from the main 
belt, intersect this schist series at very oblique angles, and probably 
have had considerable influence upon the deposition of the ore. In 
