406 W. H. Hobbs — Lime- and- Alumina-hearing Talc. 



Calculated for H 2 Mg 3 Si 4 0is 



Si0 2 61-48) 



A1 2 G 3 3-04 \ b45 " b ' i5Z 



M^O 25-54 "J 



CaO 4-19 I 



FeO 0-77 I 30 °° 31 ' 2 



MnO trace J 



HO 5-54 4-76 



100-56 100-00 



The mineral contains no nickel. 



The analysis corresponds to a normal talc in which the mag- 

 nesia is in part replaced by lime and the silica by alumina. 

 The trace of manganese accounts for the rose color of the 

 mineral which is lost on exposure to sunlight. The large 

 amount of lime present is doubtless the cause of the unusual 

 fusibility and decomposability by acids. Small amounts of 

 lime in talc are not altogether unusual, though I have been 

 unable to learn of but three analyses of the mineral, which 

 have yielded more than one per cent of lime. These are given 

 by Hintze in the list of sixty-seven analyses of talc printed in his 

 Handbuch der Mineralogie.* The three occurrences referred 

 to are Plaben, Bohemia (CaO, 1-09 per cent) ; Bergen Hill, 

 ISTew Jersey (CaO, 1*41 per cent) ; and Campo Longo (?), Tessin 

 (CaO, 3-70 per cent.) The presence of alumina in talc would not 

 seem to be so unusual, since the same list includes four occur- 

 rences of talc characterized by as large an amount of alumina 

 as the Canaan mineral. They are, Plaben, Bohemia (A1 2 0„ 

 3*27 percent); Gasteinthal, Salzburg (A1 2 3 , 5 - 37 percent); 

 Mainland, Shetland Isles (A! 2 3 , 4'14 per cent) ; aud Fahlun, 

 Sweden (A1 2 3 , 4-69 per cent). 'No occurrence is mentioned 

 by Hintze which like the Canaan mineral contains considerable 

 amounts of both alumina and lime. 



As regards the color of the mineral, it seems to be altogether 

 exceptional. Nearly all the text-books mention a rose talc from 

 Cooptown in Harford County, Maryland, but I am informed 

 by Dr. G. H. Williams that the authority for this is a state- 

 ment made by Tyson as long ago as 1837, the mineral being 

 not talc but kaemmererite or rhodochrome. Hintze mentions 

 in his Handbuchf beside the Cooptown locality, two others 

 where rose-colored talc occurs, viz : in granite at Fischbach 

 near Hirschberg, Silesia,;}: and with magnesite in clay slate at 



♦Leipzig, 1892, pp. 824-G. \ Loc. cit, pp. 819-821. 



{Traube, Min. Schles., 1888, 224. 



