W wr!ght NI> ] DEVELOPMENTS IN SOUTHEASTERN ALASKA. 61 
the vicinity of the porphyry dikes and along their contacts are ledges 
of massive galena and chalcopyrite, usually parallel with the schis- 
tosity of the formation. The principal deposit of Glacier basin is 
found between two porphyry dikes striking N. 30° W. and dipping 
northeast at an angle of 45°. Two tunnels 50 feet in length expose 
the ore body, which is about 20 feet in width. The principal mineral 
is concentrated along the foot wall. The ore is reported to carry 
values in silver, lead, and copper. 
On the Margery claims, below the basin, the deposits are essentially 
galena ores, occurring in stringers 1 foot to 5 feet in width, which 
follow a definite zone parallel with the schist. This vein system has 
been opened at an elevation of 1,500 feet above sea level by a tunnel 
40 feet in length. Farther northeast on the same claim is an open cut 
exposing a 12-foot ledge which is rich in galena and which has been 
traced several hundred feet along its strike. Assays from this are 
reported to be high in silver and gold as well as in lead. The ores are 
galena, sphalerite, chalcopyrite, native silver, cerrussite, and limonite. 
The u Ground Hog 1 ' basin claims, 4 miles north of the Margery 
claim have been developed to some extent during the year and show 
favorable assa}^ returns. The ledge is over 6 feet in width and not 
unlike the ledges of Glacier basin. 
Bradjield Canal. — On Ham Island, at the north entrance, to Brad- 
ield Canal, is a deposit of a blue, coarsely crystalline marble. This is 
'avorably situated and the marble is of good quality, containing few 
ointing cracks. The exposure is 50 feet high and 100 feet long. 
Tests of this rock have been made, and it is reported to be suitable for 
milding as well as ornamental purposes. 
KETCHIKAN MINING DISTRICT. 
Two weeks were occupied in making a hasty visit to important min- 
ng localities of this region, which had been studied in 1901 by Mr. 
Brooks. a This examination was deemed necessary, owing to the 
mange in economic conditions and to the rapid developments in progress 
it some of the mines. 
From the present investigation copper appears to be the most 
rnportant metal of this district. Gold and silver values are next in 
onsequence, both separately and in connection with the copper ores. 
)ther metals, such as lead, zinc, and nickel, are found, but will be 
>e mined, if at all, only as by-products. 
COPPER. 
The occurrence of this metal is chiefly confined to Prince of Wales 
sland, which forms the western half of the Ketchikan district. The 
>ed rocks of the island are argillites and white limestones, closely asso- 
aBrooks, A. H., The Ketchikan mining district, Alaska : Prof. Paper U. S. Geol. Survey No. 1. 
