52 ALASKAN MINERAL RESOURCES IN 1905. 
the western contact of a granite belt about 700 feet in width and parallel to the main inti 
sive stock to the cast. The mineralized band is irregular in shape and has an average wid 
of 30 feet, though at the surface workings the width appears much greater on account of 
spreading of the copper ores into the limestone hanging wall. This spreading has bet 
accomplished by surface waters, which have leached the copper from the sulphides in tl 
garnet ganguc and redeposited it in the form of the hydrated carbonate (malachite, azurit 
in the cavities and cracks of the shattered limestone hanging wall. Pockets of nearly pu 
malachite a few feet in diameter and of a columnar shape are often met with in these surfai 
workings, though they have not been found in depth. At 2,300 feet elevation, or 1 ,000 fe 
below the surface outcrops, a tunnel has Keen driven 2,400 feet in length essentially in tl 
granite epidote rock along the granite-limestone contact. At the head of the tunnel drif ; 
ha\ e been started both in the diorite ami limestone in search of ore bodies richer than thqjjj 
at the contact, hut have not yet proved successful. One of these crosscuts has penetrate 
the diorite belt for a distance of 000 feet in the direction of the Indiana claim. 
At the Indiana claim much work was in progress and a wide body of low grade ore wji 
being developed by surface mining and tunnels. The mineral deposit is similar to that of th 
New York and follows the easl side of the granite belt with limestone. It has been opena 
for several hundred feet in length and on the crest of the hill has a width of about L50 feet 
Sulphide ores of iron and copper, with small amounts of the carbonate, constitute the or 
and are disseminated throughout a garnet . epidote, and calcite ganguc. 
The Jumbo group of claims, the principal holdings of the Alaska Industrial Company 
occupy the valley of Jumbo Creek on the north slope of Copper Mountain (lig. 1). Tin 
principal developments are on Jumbo claims Nos. I, 2, and 1. On Jumbo No. I claim ai 
extensive body of magnetite chalcopyrite ore underlain by granite has been exposed by ero 
sion over an area several hundred feet in width. Below these outcrops tunnels have beci 
driven through the limestone hanging wall at various elevations to the foot -wall granite 
In the garnet-epidote contact rock, which averages 50 feel in width, the magnetite-chalcj 
pyrite ore is distributed in large scattered bodies with masses of barren rock intervening. 
The -Jumbo No. 1 claim, on the southeast slope of Jumbo basin, is located on a lode ol 
garnet-epidote rock which strikes in a southeast direction away from the limestone granite 
contact into the limestone country rock. The lode can be traced up the mountain slope for 
a distance of Dearly 1.000 feet. It varies from 10 to 2.') feet in width and often includes 
masses of crystalline limestone. Three tunnels ai points 1,700, L ,800, and L ,850 feet in ele- 
vation have been driven into the lode, and m these the ore is irregularly distributed in 
masses carrying a high percentage of copper. The erection of an aerial tramway 8,000 feet 
in length, extending from this claim to 1 Ietta Inlet , has been started and during the coming 
year large shipments of the ore will probably be made. 
The Green Monster group of claims lies 5 miles by trail south of the head of Iletta Inlet, 
at an altitude of 2,200 to 2,800 feet. At present their position is not accessible for mining, 
and even to prospeel them i^ costly and can be done only during the summer months. 
The mineral occurrence is like that on the Jumbo group and follows the contact of granite 
and limestone. The contact /one is irregular and the metal sulphides are found in small 
masses or pockets in the garnet-epidote ganguc rock. At the Diamond B claim a 0") foot 
tunnel follows this contact and exposes the garnet -epidote vein with small masses of ore along 
the first 50 feet, beyond which n enters crystalline limestone. On Green Monster No. 2 
claim a vein, composed essentially of epidote, has been opened, which at first sight resembles 
a dike cutting the limestone. It is exposed for 200 feet in length, averages feet in width, 
and has a S. 20° E. strike and vertical dip. In the tunnel, which is 65 feel long, copper ore 
was observed only in -mall amounts, though along the surface several pockets of both the 
sulphide and carbonate copper ores are exposed. 
The Corbin mine is close to tide water on the east side of Hot t a Inlet, 3 miles north of 
Copper I [arbor. The mineral deposit is a narrow vein of massive sulphide ore, carrying a few 
per cent of copper and small values in gold and silver. It follows the general structure of 
the greenstone schist country rock, striking N. 10° W. and dipping SW. 70°. The walls 
