CLASSIFICATION OF IGNEOUS ROCKS 



41 



In Class 4 the orders are subdivided as in Figure 5. The famiHes 

 are numbered from i to 12, as shown, and are divided at 0-5-50- 



Ortho- 

 syenite 

 Kf 

 Pulasklte^ 



Dlorlte 

 CaKaf 



NepEellte- 

 bearing 

 Dlorlte 



Urtlte,\. ,, ^ _ 



FerguslteV"""^"'^^^^^'^ 

 Folds 



Fig. 6. — Families in Class 2, Order 2 



95-100. The three corners, in Orders i, 2, and 3, represent respec- 

 tively oHvine, biotite and (or) amphibole, and the pyroxenes. In 

 Order 4, if thought desirable, the corners may be taken to 



