148 ALASKAN MINERAL RESOURCES IN 1905. 
During the summer of 1905 a tunnel was run into the hill somewhat lower than the lowest 
of the prospect tunnels referred to by Collier and about 80 feet above the creek. In this the 
dike was again found and is said to carry tin. Owing to water in the tunnel work was sus- 
pended until the freeze up. and the dike had qoI been crosscut at the time of the writer's 
visit. 
By stripping the debris. 3 to 10 feet thick, another dike, or a branch of the one described 
above, was uncovered about KM) feel to the south. The dike was laid bare to a width of 25 
feet, but its full thickness was Dot reached. The rock is much decomposed, hut as it is 
frozen its removal requires much drilling and the use of dynamite. Drilling in such rock is 
cas\ . but , like frozen ground, it is " shorl " in blasting and picking is slow and tedious. The 
dike is of the same rhyolitic character as the one in which the original discovery was made 
and contains inclusions of a darker intrusive, also much decomposed. 
Several small tin-bearing veins were found in the dikes, varying in width from 1 to 2 
inches, and occasionally widening out to form vugs almost entirely Idled with beautiful dark 
cassiterite crystals embedded in fluorspar and zinnwaldite (a iithia-iron mica). The vein 
matter is largely zinnwaldite and the only enlargement seen by the writer was apparently 
about 2 feet in diameter and probably at the crossing of two \ eins. The strike seemed to be 
between north and west, with a rather Hat northeasterly dip. The fluorite with the cas- 
siterite is white. Some wolframite is found in the tin veins, though in small amounts. A 
few feet south of the tin veins there arc two si null veins o\' molybdenite, one-fourth inch to 11 
inches thick. The molybdenite is in masses of small scales accompanied by fluorite and a 
mica in peculiar wedge-shaped forms whose large si sides are about one-half inch across. 
Over these wedge-shaped forms the mica sometimes has a vermiculate appearance, from 
small plates standing at a right angle to the edges of the larger individuals. In color it 
varies from a light greenish yellow to a waxy lemon-yellow (specimen T5AH99 and others). 
No tin was -ecu in these veins. The fluorite is purple and green, a small amount being color- 
less, while in the tin-bearing veins it is practically all colorless, so far as seen in the limited 
examinations. It is generally granular, but little occurring in large crystals or masses. 
The first vein filling seems to have been largely replaced by other minerals. In one speci- 
men (T5AH98) o\' mixed mica and fluorspar, containing a small amount of molybdenite, are 
a number of cavities, tin 1 largest of which is nearly 1 inch across ami 2 inches long, having the 
hexagonal form and terminations of quartz crystals. In these cavities are small cubical 
crystals of colorless fluorite and some \ ellow mica, while a few black spots, probably of pyro- 
manganese dioxide . stain the surface of both mica and fluorite. From t his specimen 
it appears that the vein was originally lined with combs of quartz crystals, after which the 
fluorite and mica were deposited, and later the molybdenite. There was little deposition 
after the removal o\' the quartz. The manganic Mains probably come from waters percolat- 
ing through the limestone, as small veins of p\ rolusite occur in a number of places. The size 
to which the quartz crystals grew would seem to sho^ that the deposition of the other 
minerals took place a long while after the intrusion of the rhyolite. 
A prospect cut in the bank of the creek exposed the same dike carrying a small amount of 
tin. A stream-cut bench in the dike 3 to 1 feet above the present creek bed, covered with 3 
feet of gravel overlain by about 8 feet of debris, was also exposed. The gravel carries angu- 
lar crystals of cassiterite and from the ease with which it can be handled would probably 
pay for working in a small way. To judge by the contour of the surface, the graved deposit 
appears to be a quarter of a mile long and 50 feet wide. 
A dike known a- the Ida Bell lode is on the west side of Cassiterite Creek just above the 
Cassiterite lode, and is believed by the owners to be an extension of the latter, although to 
the writer this does not seem proved. Instead of being one dike it is really three that have 
come up through the same fracture. The middle 5 or ti feet of the mass is a white rhyolite 
with quartz phenocrysts partially resorbed, while on each side is a smaller dike from 2 to 'A 
bet wide of a badly decomposed gray granitic rock with porphyritic feldspars. The dikes 
strike X. o0° W., with a vertical dip. A tunnel has been run about 1(H) feet along the east 
side of the dike, with a crosscut about 50 feet from the mouth. Nuiic tin is found along a 
