IMPORTANCE OF TIN DEPOSITS. 55 
percentage of cassiterite in the ore shoot may have been somewhat greater, but at the pres- 
ent level of working it is probably under 5 per cent. There is no reason to believe that the 
average richness of the ore in the deposits, considered collectively, will change with depth. 
On the other hand, decided fluctuations may take place in individual bodies. 
The metallic content of the concentrates can only be inferred from one case. While 
small selected samples of cassiterite may reach 75 per cent metallic tin, the general run of 
the concentrates will fall considerably below that figure. Of the second shipment from 
the Ross mine, 1,860 pounds averaged 72.53 per cent tin, 29,376 pounds averaged 70.31 
percent, and 4,689 pounds averaged 36.50 per cent — in other words, about seven-eighths 
averaged over 70 per cent and the remainder about 35 per cent, the average metallic con- 
tent of the whole shipment being about 66 per cent, which is a very good grade for lode 
tin. It is known that considerable care was exercised in the preparation of these concen- 
trates, so it may be that this figure is rather above the average for the region. The almost 
entire absence of other heavy minerals in the pegmatite and the purity of the cassiterite 
itself, however, make it fairly certain that careful concentration will give a clean product 
of good grade. If the figure for the Ross shipment is the average for the region, it means 
that every 3 pounds of concentrates contain 2 pounds of metallic tin. 
While subject to considerable fluctuations, the price of tin is slowly rising. The aver- 
age price of metallic tin in the New York market during 1904 was practically 28 cents per 
pound. A ton of ore containing 1 per cent of concentrates, of which 66 per cent is tin, 
contains, therefore, about $3.70 worth of tin at the above price. A maximum of the aver- 
age gross value of the ore from the shoots thus far developed in the Carolina belt is $18.50 
per ton. If abundant spodumene is ever found in close association with tin ore of good 
grade it may add to the total value of the ore, provided it can be separated and saved. 
SIZE AND EXTENT OF THE DEPOSITS. 
The width of the ore bodies is limited to that of the dikes in which they occur and is 
in many cases narrower. The average width of those ore shoots which have been explored 
is probably not over 3 feet and more likely even less. The breadth of the shoots — that is, 
the dimension in the plane of the dike at a right angle to the pitch, or greatest dimension 
of the shoot — is less easily determined by a small amount of development. Twenty-five 
feet is probably a maximum for those already known. The pitch length — the greatest 
dimension of the shoots — is thus far unknown; but indications are that the concentration 
of tin in certain parts of the dikes is controlled by factors which are variable and rather 
easily influenced by surrounding conditions, so that the ore bodies may be expected to be 
of irregular extent longitudinally. 
The fact that the ore bodies represent magmatic segregations from an igneous rock 
argues, on the other hand, strongly in favor of the probability that there is just as much 
cassiterite at a depth of 100 or 500 feet as at the present surface. It is not, however, cer- 
tain, nor even likely, that the majority of ore bodies known at the surface will continue 
without interruption to great depth. Maintenance of a fixed output as depth is attained 
will therefore mean increasing cost of exploration, aside from the commonly increasing 
costs of hoisting, pumping, and other operations with depth. 
FUTURE PRODUCTION. 
An estimate of the total amount of ore which a mining region will produce must be 
based on long and careful study and is at best exceedingly uncertain. For a region where 
so little development has been effected as in the Carolina belt any prediction of this kind 
would be idle. Certain facts bearing on the probable output of the district may, however, 
be stated. 
The prospecting that has been done during the twenty-five years since the discovery of 
tin in this region should furnish some idea of the extent and number of the ore deposits. 
While it is highly probable that some additional deposits will be found, there is no reason 
