BY H. I. JENSEN. 889 



Haiidspecimen : a dark greenish rock which on close inspection 

 is readily seen to be porphyritic, although the phenocrysts are so 

 dark in colour that they might easily escape notice at first glance. 

 This rock occurs as a sill about 20 feet thick with Permo-Car- 

 boniferous Glossopteris shales and sandstones above and below. 



Texture holocrystalline, porphyritic, with hypidiomorphic 

 granular texture approaching the panallotriomorphic. 



Constituents : the phenocrysts consist of felspar and diopside. 

 The felspar phenocrysts are lozenge-shaped and consist of anor- 

 thoclase or microcline-microperthite enveloped by a zone of 

 orthoclase. The inner portions have an extinction angle of about 

 10°, the outer zone having straight extinction. The refractive 

 index of all parts is less than that of Canada balsam. The 

 diopside occurs in idiomorphic phenocrysts. In addition there 

 are pseudomorphs after phenocrysts of hornblende. These usually 

 consist of a brown ferrite skeleton enclosing a heterogeneous mass 

 of secondary minerals, including chlorite, haematite, magnetite, 

 sericite, some isotropic analcite or sodalite (1), and zeolites. They 

 probably represent what was originally a brown soda-amphibole. 

 Some of these pseudomorph phenocrysts contain small remnants 

 of a reddish-brown very highly pleochroic mineral (apparently 

 barkevicite). 



The groundmass consists of orthoclase felspar, green ^egirine- 

 augite granules, nepheline and secondary minerals including 

 chlorite and micaceous alteration-products after nepheline, such 

 as geisikite, liebnerite, etc. 



Apatite occurs sparingly as idiomorphic phenocrysts and also 

 in smaller needles in the groundmass. 



Name : Augite-Nepheline-Syenite-Porphyry or Pulaskite Por- 

 phyry. Magmatic name, Phlegrose (see Tables i. and ii.). 



N.13. Loc: This rock occurs as a fine-grained included mass 

 of irregular shape and a couple of feet in thickness in the sill 

 rock just described (N.ll). 



Handspeeimen dark green, aphanitic. 



Texture holocrystalline, microcrystalline, panidiomorphic 

 granular. 



