2 PBOCEEDINGS OF THE NATIONAL MUSEUM vol.72 



be gypsum. Excellent material was available and was collected, but 

 all was milky. Later I received from Mr. O'Neil further specimens 

 which had glassy centers and milky rims which were apparently the 

 ejffect of dehydration. The mineral was later than the carnotite and 

 other uranium and vanadium minerals in the deposit. 



Although fairly plentiful at the point of discovery, this is the only 

 deposit in which I have found the mineral after an examination of 

 hundreds of carnotite deposits. It is entirely possible, however, that 

 some veinlets in other deposits thought at the time to be gypsum may 

 be this mineral. 



We have named the clear, glassy mineral rossife in honor of Dr. 

 Clarence S. Ross, of the United States Geological Survey. Since it 

 was found that the lighter yellow, flaky mineral differed from the 

 clear material in degree of hydration as well as in its optical prop- 

 erties, it was deemed advisable to distinguish them in mineralogical 

 nomenclature. We therefore propose to call the naturally dehy- 

 drated form metarossite, a name that refers to its relation to rossite 

 as well as to its probable mode of genesis. 



ROSSITE 



INTRODUCTION 



Rossite was found sparingly in the second lot of material obtained, 

 only as small lumps in the flaky mineral. When either rossite or 

 metarossite is dissolved in hot water and allowed to crystallize the 

 crystals have a composition corresponding to the natural rossite. A 

 chemical analysis was made on the natural mineral as well as one 

 on the recrystallized product. Inasmuch as no natural crystals of 

 rossite were found the crystallography is based entirely upon the 

 recrystallized compound. The optical properties were also deter- 

 mined upon the recrystallized mineral. 



CHEMICAL PROPERTIES 



Contributed Vy William F. Foshag 



PYKOGNOSTICS 



Rossite when heated before the blowpipe fuses easily to a black 

 bead without imparting any color to the flame. Heated in a closed 

 tube it fuses easily and gives off water. The mineral is slowly but 

 completely soluble in water from which it can be recrystallized. 

 Moistened with concentrated hydrochloric acid the mineral turns 

 mahogany red (vanadic acid) . When an acid solution of the mineral 

 is reduced with hydrogen sulphide or sulphur dioxide it becomes 

 blue in color. 



