20 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull, 213. 
It is to be noted that under the new system of gratuitous distribu- 
tion of such papers, recently ordered by Congress, the edition of this 
report was exhausted within a few weeks of its appearance. 
In Bulletin No. 178, W. II. Weed has given the result of a recon- 
naissance examination of tin deposits in the Franklin Mountains, near 
El Paso, Tex. The openings upon these deposits were too shallow to 
afford very satisfactory data as to their probable value or continuity, 
and the paper is mainly useful as proving the actual occurrence of 
tin minerals at the locality named, since the existence of such miner- 
als has often been announced without any satisfactory basis of fact. 
Bulletin No. 18(5, on Pyrite and Marcasite, by H. N. Stokes, though 
more strictly classed as a chemical paper, deserves mention here 
because it represents the results of experimental observations on the 
chemical processes which take place during the secondaiy enrichment 
of ore deposits. 
These investigations were undertaken b} 7 the division of chemistry 
and physics at the request of the geologists who had read papers upon 
this subject at the Washington meeting of the American Institute of 
Mining Engineers, and who felt that the theory needed confirmation 
from the chemical side, since, while their field studies had shown that 
certain conditions produced certain results, they necessariby could not 
demonstrate the actual chemical processes by which those results had 
been brought about. 
Part II of the Twenty-Second Annual report, forming a volume of 
nearly 900 pages, published in 1902, was devoted exclusively to reports? 
upon ore deposits. These were: 
(1) The Old Tungsten Mine at Trumbull, Conn., by W. H. Hobbs. 
This is a geological description of an abandoned mine in a locality 
which had long been classic for the fine mineral ogical specimens 
obtained there. While not important from an economic point of view, 
the paper is valuable as furnishing data with regard to the manner of 
occurrence of the rare tungsten minerals — hiibnerite and scheelite. 
(2) Lead and Zinc Deposits of the Ozark Region, by H. F. Bain and C. R. Van 
Hise. 
This report was made in response to a demand for a prompt pre-« 
liminary statement concerning the lead and zinc ores of the Ozark 
region. It is both areal and economic in character, and in some respect? 
in the nature of a reconnaissance, since it was not possible under the 
circumstances to make the study exhaustive, and work is still being car- 
ried on in the region. Perhaps its most important result is the prac- 
tical demonstration and confirmation of Professor Van Ilise's theory 
with regard to the agency of surface waters in redistributing and!; 
enriching the lead and zinc deposits of the Mississippi Valley region.' 
and the indication of the practical deductions that may be drawr 
therefrom to guide the miner in his search for ore. 
