XXIV 



PALAGONITE 



339 



situ," the spaces between the fragments being filled with pala- 

 gonite. It would seem from the peculiar erosion of the glass 

 fragments that after the crushing a liquid magma occupied the 

 interspaces, and afterwards solidified and underwent the palagonitic 

 change. 



In this connection it is noteworthy that in the sections of the 

 lower hemicrystalline portion of the flow there are shown in the 



Magma-lakelet, "25 mm. in size, magnified 290 diameters, from a basalt at Navingiri. 

 The groundmass, which is a smoky devitrified glass containing abundant felspar- 

 lathes, is coloured black. The magma-lakelet is pale yellow in the slide and 

 displays concentric lines of congelation. It behaves like palagonite. 



groundmass collections of a palagonitic material forming, as I 

 have termed them, " magma lakelets " of microscopic dimensions 

 (•25 mm. in average size). These " lakelets " are irregular in form, 

 and are not uncommon amongst a certain type of basaltic rocks. 

 One of them is figured above ; and it may be added that they are 

 best examined when displayed in a groundmass containing much 



/'. 2 



