jollier.] RECENT DEVELOPMENT OF TIN DEPOSITS. 121 
LOST RIVER LODES. 
Locution. Losi River, which enters Bering Sea 25 miles east of 
Cape Prince of Wales, rises near Brooks Mountain about VI miles 
from the coast and flows southward. The tin lodes of the Lost River 
basin are on two tributaries known as Tin Creek and Cassiterite Creek, 
^vhich flow into Lost River from the east side about 6 and 7 miles, 
respectively, from the sea. Most of the development work has been 
lone on Cassiterite Creek. The countiy rock of this whole basin is 
limestone with some intruded dikes and stocks of granite and granite- 
porphyry. Tin ore was discovered here in 1903 in connection with a 
granite-porphyry dike which extends from the hillside above Cassiter- 
ite Creek across the mountain to Tin Creek, a distance of 1 mile, 
CASSITERITE CREEK DEVELOPMENTS. 
A group of claims located along this dike, which was called Cas- 
iterite lode, was bonded in 1903 to capitalists, who in 190-1 sent in a 
veil-equipped expedition to examine the claims. Active development 
vas carried on for about a month, when the work was suspended. 
Jther bodies of ore, which were exploited late in the season, have 
>een found by the original locators for several hundred yards north- 
west of the original discovery. The field relations of the various 
irospects and croppings of tin ore are shown in the diagram, tig. 7. 
The excavations which have been made show that the dike called 
Cassiterite lode ends about 200 feet east of Cassiterite Creek, and that 
similar dike, also tin bearing, outcrops on the west side of the creek 
bout 500 feet northwest of this point. Whether or not this second 
ike is a faulted portion of Cassiterite lode has not been determined. 
The second dike extends westward for a few hundred feet from the 
oint of outcrop noted, then joins a third dike which extends north- 
estward along the top of the spur between Lost River and Cassiterite 
reek. In detail the results of this prospecting are as follows: At the 
oint of original discovery of tin ore on the west end of Cassiterite 
)de (marked b in fig. 7) a tunnel and a crosscut show an ore body 
bout 60 feet long by 15 feet wide, the lateral walls of which are the 
r ell-derined contacts of the original dike matter with the limestone. 
'he dike rock in this shoot has been altered mainly to kaolin, though 
le original texture is partially preserved. Cassiterite in line grains is 
ither uniformly distributed through this mass, but it is reported that 
ie tin content dropped below 1 per cent at the end of the tunnel. 
A second tunnel, driven on the dike about 200 feet east and 200 feet 
Ipgher on the hill, shows the porphyry in a less kaolinized condition. 
tlere it still contains some tin ore, although in smaller amounts. 
lamples taken from the croppings of the dike several hundred feet 
irther east were said to contain traces only of tin. 
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