154 ALASKAN MINERAL RESOURCES IN 1905. 
most of such feldspar as is present may have been dissolved and redeposited (specimen 
T5AH32). As silicification proceeds, the tourmaline also increases in amount , forming 
irregular masses. The tourmaline is occasionally replaced by pyrite (specimen T5AH28)] 
A gneissoid rock, a couple of inches thick, occurring along some of these fault lines is prob- 
ably a crushed portion of the granite (specimen and slide To. VI 140). Tin-bearing granite 
was struck at a number of places in this drift , but the distribution seemed irregular. About 
20 feet from the mouth another and by far the most promising ore body was found. This 
ore body follows a vertical fault with from one-fourth inch to 11 inches of gouge, striking, 
as nearly as could be determined. X. 56° W., and was formed by the replacement of the 
granite, through a space of from 12 to IS inches on each side of the fault, by quartz, tour- 
maline, eassiterite, feldspar, and a now decomposed mineral in long, white crystals (fig. 10). 
The whole vein averages between 2 and 3 feet in width and appears almost diagrammatic 
against the surrounding granite. Replacement of the granite seems to be complete and 
the mineralizing solutions evidently came up along the fault. The various minerals show 
an apparent tendency to segregate, and this applies particularly to the tourmaline and 
quartz, while the eassiterite is more apt to be associated with the quartz than the tourma- 
line, although there are generally needles of tourmaline running through the eassiterite. 
The tourmaline in irregular bunches of slender black crystals, from 6 to 12 inches in diame- 
ter, occurs either next to the fault or surrounded by other minerals. The eassiterite asso- 
ciated with the quartz forms irregular masses and bands through the body. As elsewhere 
around Cape Mountain, the granite is greatly jointed and both tin ore and tourmaline 
extend to a joint and apparently stop abruptly, the rock beyond the joint showing very 
different characteristics. 
Little that is definite can be said of the richness of the deposit, as it was struck onl\ the 
day before the writer left the vicinity and it had not been sampled, but it appears prom-; 
ising. It is reported that work during the next lew days showed the ore body to be increas- 
ing in richness. From the appearance of the vein, its width and amount of mineralization, 
and the known depth of tin veins in other parts of the world, it seems reasonable to expect 
thai it will extend downward, unless faulted oil', a fear from which one can not escape in 
such broken rocks. Some tin ore was found in the main tunnel 30 feet above, which may 
have been the same deposit, though at that point the vein is said to be small. 
About 1 mile north by west from the North Star and 2 miles northeast of Cape Mountain 
a large amount of excellent float tin ore has been picked up in the vicinity of a granite sill 
in the limestone on the Walker, Lovell & Co. prospects. The eassiterite is fine grained 
and of a peculiar shade of purplish gray with a tinge of brown, and is embedded in masses 
of fine needles of light-blue tourmaline, occasionally with portions of granite adhering to 
the mass. Lumps of the ore have been found that were estimated to weigh 400 pounds 
or over, of which by far the larger pari was tourmaline. A cabin has been built and a 
prospect tunnel run into the limestone nearly KM) feet at this point, and about a quarter 
of a mile nort h by west an open cut made which uncovers two t bin sills, one of aplite carrying 
small crystals of fluorspar (specimen T5AH24) and one of coarse pegmatite. '1 he sills are 
accompanied by about 3 feet of a fine-grained greenstone, which is probably altered lime- 
stone. It is said that assays of this greenstone made in Nome gave about 1 per- cent of 
tin, but tests by E. C. Sullivan, of the United States Geological Survey, failed to show a 
i race of tin. 
About half a mile east of Walker, Lovell & Co.'s cabin Goodwin & Carlson had run a 
prospect cut along the contact of a granite dike with the limestone country rock. Fault- 
ing is evident, there being 2 or 3 feet of crushed rock along the contact. The granite car- 
ries some fluorspar and brassy looking pyrite. The limestone above the granite is silicificd 
through an area several hundred feet wide, silicification gradually lessening in the outer 
part of the area. 
Some good float of dark, translucent eassiterite in a groundmass of light -blue tourmaline 
(specimen T5AH6a), in pieces ranging in size to over a foot in the longer dimension, was 
picked up, but none had been found in place at the time of the writer's visit. Later its 
