28 



Proceedings. 



An Apophyllite Geode; by Charles P. Berkey. 



The paper gave the results of an examination of some minerals 

 collected by C. W. Hall near Grand Marais, Minnesota. 



Complete chemical analyses were made of all the minerals of this 

 geode, and also of the diabase rock in which they were found. Grand 

 Marais is a new locality for Apophyllite, which occurs in well formed 

 crystals combining the prism, pyramid and pinacoid, ooPqo . P. oP- '^^^ 

 diabase is very much altered and bears secondary minerals in great abund- 

 ance. A chemical analysis of the diabase shows : 



Silica, Si, Og, - - - - 56.40 



Alumina, k\Oy 22.55 



Iron protoxide, Fe O, 3.75 



Iron sesquioxide, FCg Og, 14.67 



Lime, Ca O, 1.41 



Magnesia, Mg O, - - 0.74 



Water, H2O, 0.97 



Total, . . - 99.49 



Analyses of the different minerals : 



Calcite shows 99.85 per cent. CaCOgj insoluble 0.15 per cent.; Mg CO, 

 a trace. 



The analysis of the chloritic mineral is near to the composition of 

 Strigovite. 



The Pewabic Qiiartzite; by Arthur H. Elftman. 



In this paper the results of a microscopic examination and field 

 observations of a designated district in northeastern Minnesota was 

 given. The rock to which the name Pewabic Quartzite has been given is 

 placed by some geologists at the bottom of the Animike, by others in the 

 lower Keweenawan. It is older than the Keweenawan because the basal 



