LODE MINING IN SOUTHEASTERN ALASKA. 49 
I TAe Rush & Brown group of claims is located south of the first salt chuck or lake ahove 
karta Bay. The developments consist of two shafts 26 and 100 foot deep, two short fim- 
lels, and an adequate tramway and surface equipment. A railway 2 miles long, which is 
■o connect a gravity tram from the mine with a deep-water dock in Karta Bay, is in course 
If construction and will reduce transportation expenses materially. The ore body has been 
lollowed for 100 feet in depth and good ore extracted most of the way. Its extent and size, 
lowever, have not yet been determined accurately. 
Fault planes in the ore body were observed both on the surface and on the 100-foot level 
,nd limited the ore body at one point. At the time of visit a total of 1,300 tons of ore had 
>een shipped and considerable ore was in the bins awaiting transportation. 
The Mammoth group of claims is located on the north side of Karta Bay on the top of a 
ow hill 500 feet in elevation. A good trail leads from the shore to the workings, which con- 
:ist of a short tunnel and several open pits and crosscuts. The ore body is composed of 
nagnetite and garnet with variable amounts of chalcopyrite and pyrite, and is usually low 
n values. The abundance of epidote, garnet, and calcite, together with the occurrence of 
imestone bands and greenstone in the immediate vicinity, indicates that the ore body has 
>een deposited in a contact belt of limestone and probably by the pneumatolitic solutions 
emanating from the intrusive igneous rock. In position the ore body apparently caps the 
rill, and, like the Stevenstown deposit, it probably owes its peculiar form to resistance to 
irosion by glaciers. The occurrence of glacial debris, mud, and erratic bowlders, as well 
is deep glacial grooves, is evidence of the ice action at this place. The softer limestone has 
ipparently been scoured off and only the tough magnetite mass left. There is good reason 
o believe that other deposits of similar type may be found underground in this vicinity. 
SKOWL ARM. 
The Kiam mine is located near the head of McKenzie Arm, an inlet adjoining Skowl Arm, 
and has been greatly improved in surface equipment during the last summer. A gravity 
tram 2 miles in length connecting with an aerial tram 4,000 feet in length has been installed 
and suitable buildings and dock erected to insure economic handling of the ore. 
The mine is situated in a wide belt of various schistose and gneissoid rock types, striking 
about east and west, with a dip of 65°-75° N., and invaded by a number of diabase dikes, 
which trend approximately with the formation and can be traced for several miles in that 
direction. The formation is banded and consists largely of quartz-sericite schists, inter- 
bedded in chloritic and actinolitic schists. Faulting has taken place on a large scale, and 
at least three different sets of fracture systems can be defined in the mine tunnel in conjunc- 
tion with the ore body. They are also plainly marked in surface exposures, where they can 
be traced to better advantage and the actual displacement measured. 
The ore bodies which have been developed are mineralized portions of certain bands in the 
formation which contain enough chalcopyrite to make them commercially valuable. The 
copper values are not uniformly distributed and the ore bodies are irregular in shape and size. 
Pyrite, pyrrhotite, and chalcopyrite are the principle sulphides in the ore. Magnetite 
occurs in small quantities and also copper as a surficial alternation product of chalcopyrite. 
The gangue minerals are quartz, calcite, epidote, and chlorite. The ore is a low-grade smelt- 
ing ore and requires economic handling and development to give good returns. Mine devel- 
opments consist of two tunnels — a lower one 700 feet long, which was driven to undercut the 
ore body, but was finally abandoned without accomplishing its end, and an upper one, in 
which 260 feet of drifting and crosscutting had been accomplished at the time of visit. 
The Mammoth and Lake View groups adjoin the Kiam claims on the east and are located 
on the eastern extension of the schist belt. Their ore bodies resemble the Kiam deposits so 
closely in character and occurrence that the above description may be applied directly to 
them. Zinc blende was noted among the sulphides, also intrusive diorite dikes, crosscutting 
the formation at small angles. 
Several tunnels and open cuts have been driven to expose the ore and present favorable 
though small showings at several points. 
