292 Weidman and Zenker — Marignacite. 



The name marignacite is proposed for this variety of pyro- 

 chlore in honor of Marignac, who besides making other valu- 

 able contributions to chemistry, developed the method for 

 separating columbium and tantalum through the agency of the 

 difference of solubility of their double fluorides in hydrofluoric 

 acid, which is today the most satisfactory method of separating 

 these two elements. 



Analyses of Varieties of Pyrochlore. 



12 3 4 5 6 



Cb o 5 58-27 61-64 55-22 34-24 26"22 7'74 



Ta.'0 B 5-86 29-83 27*39 68'43 



Ti6 2 5-38 0-52 2-88 1-61 4-20 



SiO„ 3-10 



Fe 2 3 0-50 0-26 0-42c 



FeO 3-01 0-02 2-19 6"32 



CaO 10-93 16-61 4'10 8*87 6-00 11-80 



MgO 1-62 0-16 0-15 1-01 



Na a O 5-31 3-58/ 2-52 1'37 3-15 3'15c? 



K 2 0-36^ 0-57 trace 



Th0 2 4-96 0-20 



Ce o 3 5-50 6-895 13-33 12-34 0'17<3 



Yt" 2 3 5-07 023 



Di;0 3 0-63 



La;0 3 0-71 



U0 2 5-53« none 15-50 8-33 1-59 



SnO"„ trace 0-30 1-05 



W0 3 trace 0-30 



BeO 0-34 



Zr0 2 3-39 none 



F 3-75 trace none 1*90 2-85 



HO 110° + ) _ K _ j 5-95) ... .._ .--l 

 HO 110° — 



J 5 ' 95 I 

 ( 0-45 f 



Total 101-16 99-93 98-55 98-90 100-25 



a, with FeO; b, with La,Di ; c, with 0-13 A1 2 3 ; d, with 

 0*29 K 2 ; e, with Di ; f calculated as Na; g, calculated as K. 



1. Pyrochlore from Brevik, Norway, anal. C. F. Rammelsberg ; 

 cited by Brogger, Zeitschr. Kryst. xvi, p. 512. 



2. Koppite, from Schelingen, Baden, G. H. Bailey, J. Ch. Soc. 

 xlix, p. 153, 1886. 



3. Marignacite from Wausau, Wisconsin, anal. V. Lenher, 1906. 



4. Hatchettolite from Mitchell Co., N. Carolina, O. D. Allen ; 

 this Journal, xiv, p. 128, 1877. 



5. Pyrochlore from Batum, G. P. Tschernik, Zeitschr. Kryst. 

 xxxix, 624, 1904. 



6. Microlite, Amelia Court House, Virginia, Dunnington, Am. 

 Ch. J., iii, p. 130, 1881. 



