ART. 13 



MINERALS FROM SOUTHERN" UTAH SHANNON 



11 



composed of sepiolite. A very typical example which was found to 

 he abundant in one jilace in the iron ores of the Cerro Mercado, 

 Durango, Mexico, by Dr. W. F. Foshag has recently been analyzed 

 by him in the museum laboratory. The results of this analysis are 

 given together with two other sepiolites of similar structure and 

 composition : 



Analyses of fibrous scpioUtes 



1. Light corky snow-white masses associated with clear yellow apatite crystals in iron ore, Cerro Mercado. 

 Durango, ^Mexico. Wm. F. Foshag, analyst. 



2. Fibrous material "from a silver mine in Utah." A. H. Chester, analyst. Amer. Jour Sci , vol 13 

 p. 296, 1877. Dana System of Mineralogy, 6 ed. p. 681. ' ' 



3. "Hydrous anthophyllite" Alberton, Md. Geo. P. MerrDl, analyst. Cat. U. S. N. M. No. 62778. 

 'Asbestos and asbestiform minerals. Proc. U. S. Nat. Mus., vol. 18, pp. 281-292, 1895. 



These fibrous sepiolites are very similar to the aluminous materials 

 properly designated paligorskite^. 



The paligorskite associated with the celestite in the Utah specimens 

 at hand is, superficially, very nearly identical with the Mexican 

 material. It forms tj^pical "mountain cork" masses up to several 

 inches in diameter, which are so porous as to float on absolute methjd 

 alcohol of gravity 0.79. ^\Tiere not soiled or dirty it i^ snow-white 

 in color and is lusterless, with a dry meager and papery feel. A 

 purified sample was analyzed, giving then results and ratios of 

 columns 1 and 2 of the following table : The analysis is very similar 

 to that of Fersmann on material from the Kadainsk mine, Nerts- 

 chinsk, Siberia, as given in column 3. 



Analyses and ratios of paligorskite 



1. Paligorskite from Utah. Earl V. Shannon, analyst. 



2. Ratios of same. 



3. Paligorskite, Nertschinsk, Siberia. A. E. Fersmann, analyst. 



The above analysis of the Utah material yields rather closely the 

 formula BMgO.ALOa.GSiO.^.SH^O. The material from Kussia repre- 

 sented by Fersmann's analysis is interpreted by him as composed of 



