112 



071 two neiv Vanadium Minerals. 



[June 15^ 



adding ammonia in excess, a blue solution is obtained. Heated with 

 borax on platinum wire in the oxidizing flame the bead is yellow when 

 hot, then becomes green, and when cold is blue. In the reducing flame 

 the borax bead is bluish green, with a red skeleton of reduced copper. 



Analysis. — Two complete analyses of this mineral, freed as much as 

 possible from the matrix, gave the following results : — 







II. 



IVToQT-l 



-L.VXcaIl. 





16-78 



17-49 



17-14 





50-49 



51-45 



50-97 



Copper oxide 



19-72 



18-48 



19-10 



Oxides of Te, Zn, Mn . . . . 



2-52 



2-52 



2-52 



Lime • 



2-61 



1-64 



2-13 



Magnesia 



0-37 



0-16 



-26 





3-63 



3-63 



3-63 





0-22 



0-22 



0-22 





0-87 



1-25 



1-06 





97-21 



96-84 



97-03 



Taking the oxides of vanadium, copper, and lead, together with the 

 water, and omitting the small quantities of the other constituents, the 

 proportions are those required by the foUo^^dng formula : — 



(Pb Cu)3 O3 + 2 (Pb Cu) (OH),. 



Thus 





Calculated. 



Found. 





18-74 



18-87 



Copper oxide 



20-39 



21-02 





57-18 



56-12 



Water 



3-69 



3-99 





100-00 



100-00 



As this mineral contains no aluminium, the determination of vana- 

 dium is made by fusing the mass, after separation of copper and lead, 

 with sodium carbonate, treating the fused mass with water, and pre- 

 cipitating the soluble sodium vanadate as ammonium salt. 



In addition to the above constituents the mineral contains traces of 

 arsenic, cobalt, and sodium. 



Mottramite is interesting as forming the third term in a second 

 (doubtless) isomorphous group of phosphates, arsenates, and vanadates 

 corresponding to the well-known p3Tomorphite, mimetesite, and vana- 

 dinite group. The new group is : — 



Dihydrite .... CU3 P.Og + 2 Cu (OH),. 



Erinile ^^Mfis + 2 Cu (OH),. 



Mottramite. . . . (CuPb)3y,03 + 2 (CuPb) (OH),. 



The crystalline form of these three minerals remains yet to be 

 determined. 



