KOSSITE AND METAROSSITE; TWO NEW VANADATES 

 FROM COLORADO 



By William F. Foshag 

 Assistant Curator, United States National Museum 



AND 



Frank L. Hess 

 United States Bureau of Mines 



OCCURRENCE ". 



Contributed by Frank L. Hess 



The mineral described in this paiDer was found in veinlets cutting 

 McElmo sandstone in Bull Pen Canyon, San Miguel County, Colo.^ 

 5 miles southeast of Summit Point post office, Utah near the point 

 where the 38th parallel cuts the boundary line between Colorado 

 and Utah, and is on the western edge of the known carnotite-bearing 

 sandstones of the area. The deposit from which it came is on a 

 claim belonging to M. E. O'Neil, and to Mr. O'Neil I am indebted 

 for his courtesy in allowing me to examine the deposit, to collect 

 specimens, and for other specimens which he sent me later. At the 

 left of the entrance to one of his prospect tunnels known as the 

 Arrowhead was a considerable amount of soft, dull brownish-red 

 sandstone which owed its color to a mixture which seems to be 

 made up of hewettite, vanoxite, and roscoelite, though when mixed, 

 as in this deposit, these minerals are very difficult to identify. 

 Wherever I have seen sandstone with similar aggregates of minerals, 

 it has been soft and friable, so that cracks in which minerals may 

 form are easily developed. In certain parts of the sandstone are 

 the usual carbonized plant remains that characterize the carnotite 

 deposits in sandstones of McElmo age in the plateau region. Here 

 and there were rich spots and streaks of carnotite. Veinlets of a 

 pale yellow, flaky mineral ranging from the thickness of cardboard 

 to one-half inch and several feet long cut the sandstone at various 

 angles. Gypsum is so common in the sandstones that I at first sup- 

 posed that it formed the veinlets, but closer examination showed 

 that the mineral had only one prominent cleavage and so could not 



No. 2707.-PROCEEDINGS U. S. NATIONAL MUSEUM, VOL. 72, ART. 11. 

 55416— 2V 1 



