collier.] STREAM TIN ON BUCK CREEK. 31 
and two of them can be traced for a quarter of a mile or more. Most 
of the veiny are mere stringers, 1 or 2 inches thick and only a few 
feet long. In one instance a vein of nearly pure pyrite 6 or 8 feet 
wide was seen. Pebbles of pyrite 2 or 3 inches in diameter, oxidized 
on the outside, are found in the gravels below this vein. 
Mr. Edgar Rickard a reports on this deposit as follows: 
The source of the cassiterite can be readily traced to the slate of the [Potato Moun- 
tain] range, where it undoubtedly occurs in countless small veins and vugs, some- 
times associated with quartz and so thoroughly scattered through the mass that the 
action of the, elements has washed it from the hillsides and concentrated it in the 
streams below in appreciable deposits. 
Though specimens obtained from the gravel show that this is true, 
no veins of this kind were seen by Mr. Hess nor by the number of 
prospectors who were actively engaged in a search for tin-bearing 
veins. It is of interest to note that no granitic rocks or acid intru- 
sives of any kind have been found associated with the phyllites, nor 
have any pebbles of such rocks been found in the gravels. So far as 
the surface indications show, it appears that the tin ore has its source 
in veins which are of distinct origin from those found in association 
with granitic rocks. 
The gravel deposits in the bed of Buck Creek are from 10 to 150 feet 
wide, varying greatly in different parts of the creek. 
Cassiterite, in the form of stream tin, is distributed from the mouth 
of the creek to within a mile of its head, above which point little more 
than traces have been found. The ore varies in size from fine sand to 
pebbles weighing 13 or 14 pounds. Several pieces from 5 to 8 pounds 
in weight were seen by Mr. Hess, though the average size is much 
smaller. A few of the pebbles are perfectly rounded, but most of 
them are subangular. The ore from the claims near the mouth of 
Buck Creek is generally well rounded, while that from near the head 
is sharp and angular. In general the stream tin grows more angular 
as the head of the creek is approached. 
The color of the cassiterite varies from almost black to a light resin 
or amber; when crushed, however, it makes a light-colored resinous 
powder, by which it is readily distinguished from hematite or other 
iron minerals that are frequently mistaken for it, since they invariably 
give a distinctly red, brown, or black powder. A number of speci- 
mens were obtained with pieces of quartz and slate still attached to 
them, leaving no doubt as to the local origin of the fragments. Some- 
times small pieces of cassiterite are found inclosed between fragments 
of slate, showing that the ore sometimes occurs as veinlets in the bed 
rock. 
Near the head of Buck Creek Mr. Edgar Rickard/' in 1902, tested 
« Rickard, Edgar, Tin deposits of the York region, Alaska: Eng. and Min. Jonr., vol.75, 1903, p. 30. 
