10 CONTRIBUTIONS TO MINERALOGY. [bull. 262. 
a few inches thick was rather strongly impregnated with a yellow 
mineral resembling and probably identical with carnotite. This min- 
eral appeared also scattered through the sandstone at other points in 
sporadic small patches, sometimes visible only by aid of a lens. 
This occurrence led to the thought that the carnotite bodies farther 
west might also be associated with existing or dependent on preexist- 
ent vanadiferous sandstones. For the carnotite of Montrose and Mesa 
counties, as is stated by the French authors, occurs mixed in all pro- 
portions with quartz-sand grains, the remnants, beyond doubt, of 
former sandstone bodies, and it was soon recognized that in the car- 
notite bodies the vanadium existed in two conditions, the larger part 
by far as pentavalent vanadium in the easily soluble carnotite, and a 
smaller and sometimes hardly distinguishable portion as trivalent vana- 
dium in a much less soluble silicate which was free from uranium. 
It was hoped that, by a field reconnaissance, observations bearing 
on these points would be obtained and material assembled which would 
on analysis help to determine the nature and explain the association of I 
these two entirely different classes of mineral substances. 
The field and microscopical observations of Messrs. Ransome and! 
Spencer are embodied in the pages immediately following these intro- 
ductory remarks. Unfortunately their collections, except those from 
Placerville, came to hand so late that the chemical work on the more* 
western occurrences has been confined to the carnotite bodies alone., 
specimens of which were already in my hands. Greenish sandstones 
have been observed by Messrs. Ransome and Spencer in those regions, 
but whether any of them are highly vanadiferous, or what their con 
nection with the carnotite may be, remains yet unknown. The only 
two examined did not owe their color to vanadium. Meanwhile th< 
chemical results thus far obtained will be found in the concluding sec 
tion of this paper. 
In this place it is my pleasure to record my appreciation of th 
readiness with which the following gentlemen have supplied me wit 
material for study: Messrs. Poulot and Voilleque of Denver, Mr. A\ 
B. Frenzel of Placerville, and Mr. J. R. Duling of Paradox. Thess 
gentlemen have also not hesitated to give me all information at theft 
disposal as to cccurrence and field relations of these interesting on 
bodies. 
OCCURRENCE OF THE URANIUM ANT) VANADIUM ORES. ! 
By F. L. Ransome. 
GENERAL STATEMENT. 
In the autumn of 1899, accompanied by Dr. A. C. Spencer, who 
knowledge of the stratigraphy of the region was of great assistant 
I made a hasty reconnaissance trip into the western portions 
San Miguel, Montrose, and Mesa counties, near the Utah-Colora* 
