XIV. ABSTRACT OF PROCEEDINGS. 



in the advancement of Science, Literature, and Art, and in the amelior- 

 ation of the condition of the people. 



Signed on behalf of the Royal Society of New South Wales, 



A. LIVERSIDGE, President. 



GEO. H. KNTBBS) „ Q 



J. H. MAIDEN... } HoN - Secretaries. 



Sydney, 1st May, 1901." 



THE FOLLOWING PAPERS WERE READ : 



1. "On a new rock allied to nepheline phonolite, from Kosciusko, 

 N. S. Wales," by F. B. Guthrie, f.c.s., Prof. David, b.a., 

 f.g.s., f.r.s., and W. G. Woolnough, b.Sc. f.g.s. 



The rock described in this paper was discovered by two of the 

 authors in company with Mr. Richard Helms last January. It 

 occurs in the form of a dyke, seven feet wide, with vertical walls, 

 trending in an east and west direction, where it crosses "Evidence 

 Valley" (Helms) (the Valley of the Blue Lake, Kosciusko) at a 

 quarter of a mile above the junction of "Evidence Valley Creek," 

 with the Snowy River. The dyke is strongly intrusive into the 

 typical gneissic granite of the Kosciusko Plateau, and is perhaps, 

 of early Tertiary or Oretaceo-Tertiary age, like the soda-trachytes 

 of the Glass-House Mountains, Queensland, the Warrumble 

 Mountains, and the Gib Rock, N. S. Wales, and allied rocks 

 described by Professor Gregory as occurring at Mount Macedon 

 in Victoria. The Kosciusko rock is characterised by its large 

 proportion of nepheline which dominates all the other minerals. 

 The nepheline occurs in micro-porphyritic idiomorphic crystals. 

 The soda-augite segirine is also abundant, and there is a small 

 amount of glassy material in the base through which are scattered 

 delicate acicular crystals and microlites of felspar. A few small 

 amygdules may be noticed, not sharply marked off from the sur- 

 rounding rock ; they consist of a shell formed chiefly of analcime 

 enclosing secondary calcite. The specific gravity of the rock 

 varies from 2*43 - 2 5. The chemical composition of this remark- 

 able rock has been determined by Mr. Guthrie to be as follows: — 



Water at 100° C. = 0-23 Si0 2 =5240 



Water above 100° C. = 2-89 ALO, ... ... =1993 



