( 406 ) 



resorption-borders, arc frequently broken. This makes the existence 

 of a third phase in the cooling-process of the rock plausible, which 

 affords a striking parallelism with the existing different feldspar-gene- 

 rations described. 



To the second generation belong strictly idiomorphic crystals of 

 rhombic pyroxene, somewhat bigger than the described needles out 

 of the resorption-border, hm genetically identical with them. They 

 are often parallelly grown together; the piano lot) and 010, are 

 strongly developed and sometimes push awav the prismplanes (110) 

 (110) entirely. To the latter a distinct cleavage runs parallel; in 

 some places also a pinacoidal splitting shows itself. They have a 

 light-grey colour and display a slight dichroism. Some excellent 

 sections ±<- yielded in convergent light centrally the locus of an 

 acute positive bisectrix, so that, added to this the right extinction, 

 the enstatitic bronzitic nature of the mineral is certain. 



The groundmass, finally, is formed by a glass-base, in which, 

 besides the above feldspars, occur: ainphibole-prisms of much smaller 

 dimensions than tin- proper phenocrysts, which, however, pass into 

 them without a distinct limit of size, and as appears from the dense 

 peripheric microlite-border belong to the first generation; magnetite, 

 just as in the described dacite II 710, present in two generations, 

 and numberless bronzite-needles with the characteristic rough cracking 



(tul . Apatite occurs as inclusion in the amphibole. 



The chemical analysis of the rock yielded: 



