LODE MINING IN SOUTHEASTERN ALASKA. 59 
quartz stringers were followed by drifts. Tests have been made on 
the ore obtained in the 10-stamp mill on the Red Wing group, just 
below this company's property/ but apparently the results were not 
encouraging. 
Prospecting on the divide between Windham Bay and Endicott 
Arm has revealed several quartz veins, carrying moderate values, but 
their inaccessibility and distance from tide water render them of little 
economic value at present. 
ADMIRALTY ISLAND. 
The mining interests on Admiralty Island have changed but little, 
and on the two properties, the Portage group at Funter Bay and the 
Mammoth group at Young Bay, there has been a notable lack of 
development. 
The deposit on the Portage group is a mineralized band of chlorite- 
mica schist, cut by quartz-calcite veinlets and containing small masses 
and particles of copper and iron sulphides scattered across a width of 
about 40 feet. This band has been exposed by an open cut, and the 
ore is apparently of low grade. Just below the open cut a tunnel was 
started to undercut the lode, 40 feet in depth. When visited, this 
tunnel was 30 feet in length and had not reached the ore. 
Two miles southeast of the Portage group investigations have been 
in progress by the Mansfield Gold Mining Company on copper deposits, 
consisting of several quartz ledges, 3 to 6 feet wide, 100 feet or more 
apart, and striking northwest, parallel with the trend of the country 
rock. These deposits carry considerable chalcopyrite and pyrrhotite, 
also some galena and sphalerite. The main vein outcrops at 1,380 
feet elevation on the north slope of Funter Mountain, and at this point 
has been exposed by a 20-foot tunnel and surface stripping. At 550 
feet above tide water a crosscut tunnel has been started to investigate 
these veins in depth, and work in this tunnel will be furthered during 
the winter months. 
On the Mammoth group, to the southeast of the Portage group and 
on the same mineral zone, the annual assessment work alone was done. 
SITKA MINING DISTRICT. 
GEOLOGY. 
The geology of the Sitka district, which includes Baranof and 
Chichagof islands, is comparatively simple. The bedded rocks of the 
islands are in the main broadly folded Devonian limestone and chert 
beds with interstratined basaltic flows, and overlying these along the 
outer coast are slate-greenstone strata, which in turn are overlain by 
a wide belt made up of pre-Cretaceous graywackes and conglomerates. 
The most recent rock formations are represented by the lava beds 
