On Nepheline-basalt from "i'ingc-mon, Manchuria. 



11 



swim in this scanty base, being rudely arranged tangentially 

 around the nearly isometric crystals (see PL l.ßg. 3) of nepheline, 

 thereby producing the appearance of a leucite-melilite rock. 



The rock is nearly holocrystalline, a variety typically rich in 

 nepheline and simple in mineralogical composition. If the 

 nepheline were absent, the mineralogical composition of the rock 

 would correspond to a limburgite, to which the texture has a close 

 resemblance, as may be seen in the photomicrographs, PI. l.ßgs. 2 

 and 3. The order of crystallization of the rock-components is 

 shown in the following scheme: 



Relative Duration 



The chemical analysis of the rock from Tsao-sluli-err was 

 undertaken by ^lessrs. S. Shimidzu and T. Ohashi, of our Geolog- 

 ical Survey, to whom I would acknowledge my indebtedness. The 

 result is given below : 



1) Two generations. 



2) Two generations (not seen in the photomicrograph). In the older and larger ones 

 crystals of nepheline are poikilitically enclosed in the substance of augite (0.6 mm long) which 

 sometimes suffers magmatic corrosion. The augite is so fully stuffed with octahedra of 

 magnetite that the whole presents the appearance of some rhonite crystals, though the substance 

 of the host is here pyroxenic 



