YORK TIN REGION. 149 
horizontal fault zone on the east side of the dikes and more is said to have been found at the 
end of the tunnel. Quartz veins an inch or less wide, carrying wolframite and probably 
some tin, occur in a silicified portion of the dike about 66 feet wide, 50 feel from the mouth 
of the adit. 
About 500 feet north of the Tda Bell lode is another dike of rhyolite, which resembles 
that of the Cassiterite lode, and is called the Bear lode. It has an east- west strike, and on 
top of the hill between Cassiterite Creek and Lost River is about 35 feet broad. A tunnel 
about .V) feet long was run into it from the creek level and a winze sunk 69 feet along t la- 
west or hanging wall. This was filled with water, so that it could not be entered. It was 
said that many small tin-hearing veins were found running in various directions, mosl of 
which were near the middle of the dike. Fragments of rock in the dump showed veins 
of almost pure cassiterite and quartz aboul one-half inch thick and other veins carrying 
cassiterite, chlorite, and some wolframite up to 1 \ inches thick (specimens T5AH82, 
T5AH83, and others). 
At the creek level the dike is much decomposed and considerably iron stained. Where 
exposed on the top of the hill it is hard and shows no tin. About 275 feet to the north, 
along the top of the hill, there is ;i similar dike, 6 feel wide, striking N.60° W. No tin has 
yet been found in it. It is noticeable that no tourmaline has been found in these deposits. 
The Dolcoath lode is a narrow dike about 2', feet wide, 1 mile X. 15° E. of the Cassi 
terite lode. It strikes X. 70° E. and dips 65° X\Y. A crosscut on the Discovery claim 
showed the dike to be about 2! feet thick. On the hanging wall i- a deposil of arsenical 
and antimonial pyrites mixed with feldspar, from (i to 12 inches thick. The feldspar 
carries some cassiterite, which also occurs in « ■ ; i b ■ i t < ■ and impregnates the limestone (speci 
mens T5AH72 to T5A1175). Topaz in incomplete crystals one half inch broad accom 
panics the cassiterite. The feldspar is of ;i lighl pinkish-graj color, and would he sup- 
posed to be merely vein matter were it not thai 100 feet to the east, along whal seems 
to be the same dike, the dike matter ha- been entirely changed and -how- only li^ht- 
colored orthoclase-feldspar, quartz, and tourmaline, so that what seems here to he a vein 
may he the feathering out of a second dike in the same fracture. In places in the lime- 
stone on the loot wall side of the dike cassit< rite forms a vein I or 5 inches thick. There 
are signs of faulting in the vein- and joint planes run from the lime-tone across the dike. 
An assay of the feldspar-quartz-tourmaline portion of the dike i- said to have given 1.15 
per cent of tin. Tin ore is also reported to have been found in floal on the same dike at 
its outcrop near Lo-t River. 
At a number of place- in the neighborhood of Cassiterite Creek the proximity of dikes 
is indicated by the va-t number of siliceous veinlets in the limestone. Every minute 
crack has been filled by silica, and in weathering the outer portion of tin- limestone i di 
solved, leaving a skeleton of the silica with hard, jagged edges. Man} of these vein 
not over one two-hundredth of an inch in thickness and in those that are thicker epidote, 
vesuvianite, garnets, fluorspar, lithia micas, cassiterite, and probably other minerals often 
make their appearance. Close to the Cassiterite lode there an- many small veins from 
one-eighth to 1 inch thick of zhmwaldite, one of the lithia micas, crystallized a1 right 
angles to the wall-, carrying also a little fluprite, cassiterite, and wolframite. There are 
other quarter-inch veins of a mineral which on analysis \>\ W. T. Schaller, of the United 
State- Geological Survey chemical laboratory, was found to have the composition of mar 
garite, hut which doe- not -how the fine cleavage of margarite, and seems to be isotropic. 
Float ealcite, containing cassiterite, has been picked up a number of time-. The mineral 
ization has been yery great, hut ha- taken place in a comparatively restricted area, i »p< 
cially that part which -how- cassiterite, and in this fad lie- the great) -' ground fordoubl 
ing the future development of large tin deposits in this district. Thre< in bearing 
vein- of noticeable and possibly workable size occur in the lime-tone. These will he 
described in some detail. 
There i- a quartz vein about 1 babe- wide dipping o0° S. an eighth of a mile al 
the Cassiterite lode, on what is known as the Jupiter claim, but it has been traced onb. a 
