66 



Classification. 

 Class V. Order 1. Section 4. Rang 1. Section 1. 

 Subrang 1. 



Magmatic name, Gordunose. 



Notes on the Analysis. 

 It will be seen from the analysis that the rock contains 

 noticeable percentages of A1 2 3 , K 2 0, and Na 2 0. These 

 constituents have been allotted to form orthoclase, albite, and 

 anorthite. These minerals do not occur in the mode, conse- 

 quently the Al 2 O a , K 2 0, and Na 2 are present in the ferro- 

 magnesian minerals. 



In the analysis of the olivine extracted from this rock no 

 alkalies or alumina were detected, therefore these constituents 

 must be combined in a complex fashion in the pyroxenes. 



Chemical Diagrams. 

 The following chemical diagrams have been inserted to 

 convey a better idea of the relative amounts of the con- 

 stituents present. They are respectively the Mugge and 

 Brbgger diagrams. 



The Mugge Diagram 



nqo 



fll 2 3 



The Brogger Diagkam 



