276 PETROLOGICAL ABSTRACTS AND REVIEWS 



Endell, K., und Rieke, R. "Ueber die Bildung des Cristobalits 

 aus Quarzglas und ueber seine reversible Zustandsanderimg 

 bei 230," Tschermaks Min. u. Petr. Mitt., XXI (1912), 501-12. 



Endell, K., und Rieke, R. "Ueber die Umwandlungen des 

 Kieselsaureanhydrids bei hoheren Temperaturen," Zeitschr. 

 anorgan. Chemie, LXXIX (191 2), 239-59. 

 The authors show that quartz, amorphous silica, and quartz glass 



change to cristobalite at high temperatures and in the absence of 



mineralizers. 



A. J. 



Endell, X., und Smits, A. "Ueber das System SiOa," 

 Zeitschr. anorgan. Chemie, LXXX (1913), 176-84. 

 A further contribution to the inversion of quartz glass to (i- 

 cristobalite, quartz glass to )8-quartz, and /8-cristobalite to y8-quartz. 



A. J. 



Endell, K. Ueher die Umwandlungen der Kieselsdure bei hoheren 

 Temperaturen. Leipzig, 1913. Pp. 6. 

 An address before the eighty-fourth meeting of the Gesellschaft 

 deutscher Naturforscher und Aertzte zu Miinster giving a summary of 

 the author's work on the inversion of Si02 at high temperatures. 



A.J. 



Endell, K. "Ueber Granatamphibolite und Eklogite von 

 Tromso und vom Tromsdaltind," Centralbl. f. Min.. etc., 1913? 



129-33- 

 Garnet amphibolite and eclogite from northern Norway are described. 

 A chemical analysis of the former, calculated in the Osann system, gives 



^i -5^5/13 -s- 



A. J. 



Fenner, Clarence N. "The Various Forms of Silica and Their 

 Mutual Relations," Jour. Washington Acad. Sci., II (1912), 

 471-80. 



Shows that either tridymite or cristobalite may, under certain con- 

 ditions, such as those which induce rapid crystallization, form at tem- 



