150 TRANSACTIONS OF THE [MAR. 18, 
of tin-ore which comes from Zacatecas, Mexico. One of our old 
students, Mr. Banks, has just come back from there, bringing 
many specimens and having examined a considerable territory. 
In that region there is some stream-tin, but not like that found 
elsewhere. Generally it occurs in drops and knobs, with a 
fibrous internal structure, and the masses are of concretionary 
character. This is different; for it is distributed irregularly 
through a rhyolite rock that has been evidently very much 
digested with hot water. The quantity is often large, and yet 
there, as elsewhere, it is a problem whether there is any deposit 
that can be worked with profit. I think the general impression 
has been that it would not pay to do regular mining there. 
Probably the only way to obtain tin profitably is to employ the 
natives to wash it out, working the deposit as a placer. 
Tin is not nearly so rare a material as it has been said to be. 
Lumps of cassiterite are often found in the gold-gravels of 
Idaho, and there are veins of tin-ore in the Temescal mine near 
Los Angeles, Cal.; but Mr. Stokes spent a year there, and, after 
fairly testing the deposit, he came to the conclusion that it would 
not pay to work it. So we are not so very destitute of tin in 
North America, but the conditions for the profitable mining of 
it are peculiar. It must be where, if possible, nature has decom- 
posed the rock; then labor must be cheap, if we are to come in 
competition with the sources of supply in Tasmania and else- 
where. The conditions described to us by Mr. FuRMAN in North 
Carolina would appear to be favorable, and it seems as though 
the chances were better for working the deposits there than 
in other places. 
In regard to the Black Hills, we have had a great variety of 
testimony. Mr. Bailey, who was one of the first heralds of the 
great deposit of tin there, has told his story in this room. He 
brought before the Academy a Splendid series of specimens, and 
claimed that the deposits of tin from which they were taken 
were unparalleled; but, though that was several years ago, no 
tin has yet come to market from that region, even after the ex- 
penditure of much money and mining on a large scale. The 
attempt has not yet been a success there. This North Carolina 
deposit promises better than any I have known elsewhere in this 
