LODE MINING IN SOUTHEASTERN ALASKA. . 71 
are on Jumbo No. 4 claim, where three tunnels crosscut the contact 
zone and expose ore bodies at 1,650, 1,770, and 1,876 feet above sea 
level, and are themselves connected by raises. Similar ore masses 
have been opened by surface cuts at 2,000 feet elevation. From this 
mine a short aerial and surface tram connects with an aerial tram 
8,228 feet long, over which the ore will be transported to 3,000-ton 
bins built on a wharf at tide water. 
Other ore bodies developed in former years by this company are 
Jumbo Nos. 1 and 2 claims, and on the Green Monster group to the 
east, but these were neglected last year and mining was confined to 
the above-described property. 
A mile to the north of the Jumbo claims are the Houghton claims, 
located along the granodiorite contact on similar chalcopyrite-magnet- 
ite deposits. These were transferred within the year to the Cuprite 
Copper Company, which has undertaken large developments. 
Early in the year the Corbin property, 3 miles north of Copper 
Harbor, on the east shore of Hetta Inlet, was transferred to the Alaska 
Metals Company, which has begun developments, consisting essen- 
tially in the erection of buildings, a compressor plant, and wharf. 
The ore body is a narrow vein of massive sulphide ore, carrying but 
a slight percentage of copper and small values in gold and silver. It 
follows the general northwesterly structure of the greenstone-schist 
country rock. At a point 45 feet from the mouth of the tunnel to the 
south the vein narrows to a mere seam, and in the shaft, 22 feet below 
the surface, it was faulted. From all indications the deposit appears 
to be a small ore shoot, less than a hundred feet long and 3 feet wide, 
pitching at an angle of about 60° NW. 
At the Copper City mine, 8 miles south of Copper Harbor, opera- 
tions began in May and continued throughout the year. The ore 
body is a narrow vein of massive sulphide ore, occurring in the slate- 
greenstone schist country rock. The vein parallels the vein structure 
and varies from 1 foot to 5 feet in width. It is crosscut by dikes of 
diabase, which apparently are later than the deposition of the ore. 
Several shipments of the ore were made to the smelter at Tacoma 
during the year. The principal feature in the mine workings was the 
development of the vein below the 100-foot level. Along this level 
the ore body wedged away rather suddenly and was found to be dis- 
placed for a short distance toward the foot-wall side. At a point in 
the drift 60 feet northwest of the shaft a winze was being sunk on the 
vein to the 200-foot level, and in this a good width of ore was reported. 
GRAVINA ISLAND. 
Copper-bearing deposits are known to occur on both the south and 
north ends of Gravina Island. The properties at Seal Bay and on 
Dall Head were prospected to some extent during the summer, and 
