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Poicilitic intergrowths of astrophvllite with felspatoids occur in 

 adjacent astrophvllitelnjaurites, wliere numerous idiomorphic pseudo- 

 morphoses of zeolites and analcime after nepheline, and also aegirine 

 are enclosed by large crystals of astrophvllite. In the iujauriteporphyries 

 from Wijdhoek (701) which are rich in pectolite, strongly pleochroic 

 crystals of eucolite poicilitically enclose nepheline and sodalite, whereas 

 sometimes they are intersected by lath-shaped felspars as is found 

 to occur with the augites of the diabases. 



2. Mutual intergroivths of felspars and felspatoids. 



In the aegiriueamphibolebiotitenephelinesyeniteporphyries mentioned 

 sub 1, we find besides the interlaced crystals of the dark minerals, 

 numerous large crystals of idiomorphic nepheline, which only between 

 crossed nicols contrast with the tinegrained mixture. Sometimes 

 this nepheline is free from inclusions, sometimes it is filled with 

 short laths of felspar. Some of the crystals of nepheline are enclosed 

 hy an amphibole skeleton and themselves enclose numerous small 

 crystals of felspar and biotite. All transitions from nepheline free 

 from felspar to nepheline rich in felspar can be seen ; in an inter- 

 mediate form the inclusions are limited to the marginal parts of the 

 crystal. 



Consequently in this rock real plienocrysts of nepheline must have 

 been crystallized before the finegrained mixture was formed. 



In a lesser degree the enclosing of felspatoids by felspars, and the 

 crystallization of nepheline with angular forms in the spaces between 

 the felspars, is a common phenomenon in the rocks of this region. 

 In these rocks also occur large felspatoid crystals, enclosing the 

 smaller ones. 



Macroscopically the rock is mediumgrained with lightgreen fels])ars 

 and lightbrown nepheline; aegirine is very subordinate. Under the 

 microscope we see the peculiar structure between crossed nicols : the 

 crystals of idiomorphic nepheline and sodalite which are vei-y abundant, 

 the microperthitic felspar, and the aegirine enclose innumerable small 

 idiomorphic and rounded crystals of nepheline (and sodalite) ; the 

 crystals which are rich in inclusions are reduced to skeletons. The 

 felspatoids are partly decom|)osed to cancriuite : we find complete 

 pseudomorphoses, with the form of the original crystal, which consist 

 of one crystal of cancriuite with sieve structure. It is interesting 

 that the enclosed small ci-ystals of felspatoids are not altered at all; 

 there must be a cause why they could resist the CO, bearing 

 agencies, may be as a result of changed chemical composition of the 

 magma during the crystallization. 



