LODE MINING IN SOUTHEASTERN ALASKA. 
51 
and in the rock itself. The ore bodies are several hundred feet in width 
and several thousand feet in length. No similar deposits have been 
discovered elsewhere in Alaska. 
The copper deposits prominent on Prince of Wales Island can not 
be classed under the above-mentioned forms of occurrence. They are, 
with few exceptions, irregular lenses or masses of chalcopyrite ore, 
many of them rich in magnetite, and occur either as replacement or 
contact deposits adjacent to a granitic intrusive mass, and more rarely 
as heavily impregnated portions of schists. 
GOLD. 
OCCURRENCE. 
Although gold is universally distributed along the coastal moun- 
tains of southeastern Alaska in lodes, and less commonly in placer 
deposits, there are relatively few localities which show a sufficient con- 
centration of auriferous minerals to make valuable ore bodies, and in 
these places the ore is usually low in grade. The possibility of mining 
such ores, however, is obvious when one considers the available water 
power and favorable means of transportation the country affords. In 
the gold-quartz veins or lodes the gold is found both in the native 
state and also combined with metallic sulphides, which usually pene- 
trate into the inclosing country rock. These quartz-filled fissures 
were formed subsequent to the general metamorphism of the coastal 
mountain range and after the granodioritic invasion, and their content 
is in genetic relation to the intrusive rock. 
PRODUCTION. 
The subjoined table shows the gold produced in southeastern 
Alaska in 1905. The placer deposits yield but a very small proportion 
of the gold production, their total output in 1906 being less than 
$20,000. Placer mining was advanced at only two localities, in 
Silverbow Basin and at Windfall Creek. 
Production of the gold mines in southeastern Alaska, 1905. 
Gold. 
Silver. 
Average per ton. 
Ore mined. 
Amount. 
Value. 
Amount. 
Value. 
Gold. 
Silver. 
Amount. 
Value. 
Amount. 
Value. 
Tons. 
1,305,316 
Ounces. 
162,353 
$3,335,406 
Ounces. 
31,110 
$18,789 
Ounces. 
0.118 
$2.44 
Ounces. 
0.023 
$0. 014 
To the above figures must be added the gold produced from the 
copper mines, which amounted to $71,170 in gold and $16,021 in 
silver. It should also be stated that nine-tenths of the total output 
was from the Treadwell group of mines on Douglas Island. 
