1887.] ^" [Gentb. 



The analyses gave : 



0.240 



0.125 



100.05 100.17 



For comparison I give the mean result of three analyses of Penfield, 

 Rammelsberg's analysis of cuprodescloizite, "Velasquez de Leon's analysis 

 of ramirite and Frenzel's analysis of tritochorite. 



100.17 — 99.62 — 101.02 — 99.G55 — 100.17 



]\Iy analyses agree very closely with those of Mr. Penfield and give ex- 

 actly the formula of descloizite Pb^ [HO] (VAs P)Oi + (ZnCu), [HO] 

 (VAsP)O,. 



In Rammelsberg's analysis the greater portion of arsenic pentoxide has 

 evidently been weighed with the vanadium pentoxide. 



In De Leon's analysis the determination of water is omitted, while 

 otherwise the results agree with ours although the copper oxide is about 

 two per cent higher. 



The physical characters of the mineral and some of the determinations 

 of the trichorite agree so closely to cuprodescloizite that it would be de- 

 sirable if Dr. Frenzel would repeat his analysis. 



III. Pybite pseudomorphous after Pyrrhotite. 



In a highly interesting and important paper on "Natural solutions of 

 gold, cinnabar and associated sulphides, by Geo. F. Becker" (Am. Jour. 

 Sciences [3] xxxiii, p. 199 ff), the author shows the solubility of gold, cin- 

 nabar, pyrite and other sulphides in alkaline solutions containing sulp- 

 hydrates, and suggests that these minerals, found at Steamboat Springs 

 and Sulphur Bank and similar occurrences, have been deposited from such 

 solutions. 



