106 



Oobaltiferous Smitlisonite from Boleo, LowerOalifomia, México 

 BY C. H. WARREK. 



[American Journal of Science, August 1898). 



This mineral was sent to this laboratory for idenlification, by Mr. 

 Geo. W. Fiss of Philadelphia, and was supposed to be the rare hy- 

 drated cobalt carbonate, iíemm^'/omíe, the composition ofwhich is not 

 known. The mineral consist of little crystalline particles of a delicated 

 pink color, imbedded in gypsum and associated with a little atacamite. 

 The mineral was first carefuUy sellected from all material of a green 

 color by hand'picking, and was then crushed and sifted to a uniform 

 grain, and treated with the heavy solution to sepárate the lighter por- 

 tion. The heavy portion when examined under the microscope was 

 apparently very puré. The specific gravily was found to be 3.874, and 

 * analysis gave the following results: 



.839 

 .838 



100.17 



Regarding the small amount of GuO, H'^0 and Gl as impurities, re- 

 sulting possibly from a slight admixture of atacamite, the ratio of CO'': 

 (Zn+Go+Mn+Fe+Mg)0 is .839: .838 or almost 1:1. indicating 

 that the mineral is a normal carbonate, and essentially a zinc carbo- 

 nate, Smithsonite, in which the zinc is partially replaced by cobalt, 

 manganese aad magnesium. 



Laboratory of Mineralogy and Petrography, 

 SheiBeld Scientific School. 



