AET. 11 nOSSITE AND METAROSSITE FOSHAG AND HESS 9 



The dispersion is very strong ; the emergence of an optic axis appears 

 as a broad band of colors. The high dispersion manifests itself in 

 bright-colored flashes when the crystal is mounted and revolved on 

 the goniometer. 



METAKOSSITE 



GENERAL 



The mineral that occurred most abundantly in the material re- 

 ceived is what we here call metarossite. It forms small yellow veins 

 in a light gray and friable sandstone, is coarse, platy in habit, but is 

 soft and friable. Occasionally within the center of masses of meta- 

 rossite one can find small glassy kernels of rossite. The relation of 

 the metarossite to the rossite suggests that it is a dehydration prod- 

 uct of that mineral. As will be evident from the analyses given 

 further on, the mineral is a distant hydrate and not a partially 

 altered rossite. Two analyses made on different lots agree very well 

 with each other and with the theoretical values for the formula 

 assigned to it: CaO.V2O5.2H2O. We feel justified, therefore, in 

 assigning a distinct name to this compound. 



CHEMICAL PROPERTIES 



Contributed l)y William F. Foshag 



PTEOGNOSTICS 



The behavior of metarossite before the blowpipe is entirely similar 

 to the rossite. It is, however, somewhat more slowly soluble in 

 water. Its chemical reactions are identical with those of rossite. 



ANALYSIS 



Abundant material was available for analysis. (No. 95331, U. S. 

 N. M.) Two different samples were submitted to chemical analysis, 

 one from the first lot received and another from the second lot. 

 The samples were carefully chosen, only the larger and purer cleav- 

 age fragments being selected. Upon examination under the petro- 

 graphic microscope the large majority of the flakes were clear and 

 transparent, but the very large grains had a somewhat muddied ap- 

 pearance, due to included air. There were occasional grains of sand 

 from the inclosing sandstone, estimated to amount to about 2 per 

 cent. The analysis was carried out according to the scheme outlined 

 under rossite, wit^ the following results : 



