368 



University of California Publications. 



[Geology 



only this difference (except water) that Al:Fe = 3:4. The con- 

 stitution is that of a glaucophane : 

 r NajSiO, 



) FeSiO, Mg:Ca = 6:l 



1 2MgSi0 3 . Al:Fe=3:4 

 ' (AlFe) 2 Si s 8 



as P. Groth* has stated; but because of the characteristic prop- 

 erties and chemical constitution, I propose to retain the name 

 crossite for such glaucophanes with transverse axial plane. I 

 add here that this little variation in the chemical composition 

 (Fe ^ Al) has a great influence on the cohesion, so that crossite 

 gives etch-figures quite different from those of glaucophane. 



Dr. A. C. Lane has remarked (in a letter to Dr. Palache, No- 

 vember 27, 1895). and I can confirm the observation, that crossite 

 is not identical with Cross's amphibole. f Cross has identified, 

 with good reason, the blue amphibole of Silver Cliff with La- 

 croix's crocidolite. 1 I was not fortunate enough to find schists 

 with crocidolite, such as have been described by Lacroix, S. Fran- 

 chi,§ C. Smith, 1 1 etc. Professor Louderback has shown me, how- 

 ever, a quartzite with crocidolite (?) (from the Coast Ranges) 

 which is very similar to the description of Lacroix. I may add, 

 however, that among the erocidolite-like minerals there are sev- 

 eral kinds of amphiboles. 



RJiodusite (Abriachanite) . — Almost all mineralogists have 

 considered Foullon 's rhodusite** as being related to glaucophane. 

 Foullon himself describes it as an asbestos variety of glauco- 

 phane. According to the occurrence (in a "breccia" and in the 

 " Asbest-artiger " schists of eocenic flyschj, form and few prop- 

 erties given, and especially according to the analyses, rhodusite 

 is a member of the glaucophane group of amphiboles related to 

 crossite and crocidolite, as Rosenbusch has emphasized in his new 



* P. Groth. Tableau des mineraux d'apres leurs composition ehimique, 

 1904. Edition Pearce and Jourowsky. 



| W. Cross. Note on some secondary minerals of the amphibole and 

 pyroxene groups. Amer. Jour. Sci., XXXIX. May, 1890. 



X A. Lacroix. Sur la crocidolite. Bui. d. 1. Soc. de Mineralogie, Paris, 

 1890. XIII. 10. Mineralogie de la Prance, p. 691, 1893. 



§ S. Franchi. Gontrib. alio Studio delle roccie a glaucofane. Extr. 

 del. Bollettino del B. Gomitato geologico, 1902. Xo. 4. 



II C. Smith. Untersuehimgen einiger Gesteine. Zeits, fur Kryst. 1904, 

 38, p. 201. 



** In Bukowski 's paper in Sitzungsberichte d. k. Akademie, Wien 1890. 

 p. 226. PL B. Foullon, Ibidem, 1891, 100 p. 169. 



