collier.] SUMMARY OF ECONOMIC GEOLOGY. 37 
climate and the cost of labor, the probabilities are that further devel- 
opment will prove some of the deposits to have commercial value. 
The ore occurs in both alluvial deposits and in ledges. The ore of 
the alluvial deposits has been traced in some cases to small veinlets 
and vugs in the slate country rock, where it has no visible connection 
with intrusions of granite or other igneous rock, and in others to well- 
defined dikes or veins of greisen. This lode ore is associated with 
granite or other siliceous, igneous, intrusive rocks, that have been 
altered to true greisen like that occurring in nearly all productive tin 
regions. 
In one case the cassiterite occurs disseminated through a greisen 
composed of quartz, calcite, fluorite, and lithia mica. In another case 
the tinstone is intimately associated with tourmaline contained in veins 
in the granite. 
The granites in which tin ore has been found are intruded in lime- 
stones of Silurian age in one case and probably of Carboniferous age 
in another. Similar bodies occur northeastward from York for a 
distance of 100 miles. Minerals associated with the tin ore in the 
York region, such as fluorite and tourmaline, have been found in sev- 
eral of these granite areas, and tin ore has been reported from some 
of them, but its existence outside of the Y r ork region has not yet been 
proved. 
Some of the promoters of mining enterprises have expressed a 
desire to install immediately a complete outfit for milling and smelting 
tin ore at some point in the Y r ork region. The many fiascos resulting 
from the building of mills and smelters before the extent of ore bodies 
had been determined are well known to anyone familiar with the his- 
tory of mining in the United States, so that the folly of this plan is 
evident. Even after the ore is proved to exist in sufficient quantities 
for mining a careful study must be made of the ore itself, and of the 
conditions as affected by climate, wages, fuel supply, and transporta- 
tion, before either the proper place or method of treating the ores can 
be determined. The erection of a smelter at present would seem to 
be ill advised, if for no other reason than because no estimable supply 
of ore exists. In estimating the value of tin ores in this northern 
region several facts must be borne in mind. The region is devoid of 
timber and is accessible by ocean steamers, at the longest, only from 
the first of June to the end of October. Harbor facilities are poor, 
and all supplies and wages are high. On the other hand, the con- 
struction of railroads and wagon roads would not be difficult, and, if 
demanded, would require comparatively little outlay of capital. 
TRANSPORTATION ANT) FUEL, SUPPLY. 
In view of the possible developments of tin mining in this region 
the questions of transportation and harbor facilities become important. 
