BY W. H. TWELVETKEES. 45 



The garnet is fresh, zonal ly marked, highy idiomorphic, and 

 occurs not only as phenocrysts, but also as a constituent of 

 the trachj^toid groundmass." 



The nosean mineral, though plentiful in many specimens 

 of the rock, is rare in others, and is sometimes quite 

 absent. A suggestion was made to me in Victoria that 

 the identification of the nosean might be incorrect. I felt 

 satisfied that no mistake had been made, and Professor 

 David, lo whom I showed a slide, confirmed the reference. 

 Professor Rosenbusch also recognised nosean, or haiiyne, in 

 a slide which was sent to him. He says : — 



" Whether haiiyne (rich in Ca) or nosean (rich in Xa) is 

 present cannot be determined without chemical investiga- 

 tion, but one of these two minerals is undoubtedly here." 



I do not know that nosean or haiiyne has been recorded 

 elsewhere in Australasia. 



Mount Mary is situate to the west of Lovett, and a trip 

 made to it disclosed the occurrence of other members of the 

 alkali series. The elaeolite, or alkali syenite porphyry, with 

 the biscuit-like felspar phenocrysts, was seen at the Mount 

 Mary mine, and a little above it the hillside was strewn with 

 stones of green tinguaite, or fluidal tinguaite porphyry. 

 The summit is occupied by a grey tinguaite porphyry, with 

 large glassy sanidine felspars, and rich in fresh-looking 

 melanite, but poor in nepheline. It occurs in contact with 

 Permo-Carboniferous sediments, impregnated with pyrites. 

 Near the summit are outcrops of the alkali syenite 

 intrusion, which apparently forms the mass of the moun- 

 tains. 



On the Back Road the plutonic rock is well exposed. With 

 respect to this Professor Rosenbusch writes : — 



" It consists of dull orthoclase, fresh and beautifully 

 zoned albitic felspar, with basic margins; augite (f- ^^48°) 

 green in colour, with occasional narrow margins of deeper 

 tint passing over into aegirine aagite. The rock belongs to 

 the alkali augite syenites, though it does not agree with 

 either Pulaskite, Nordmarkite, Umptekite, or Laurvikite, 

 &c. ; in fact, it does not correspond exactly with any of the 

 numerous rocks of that series. According to its dominant 

 structure, I would call it either an alkali syenite with 

 porphyritic facies, or an alkali syenite porphyry with 

 granular facies." 



The visit of the members of Section C. to Port Cygiiet 

 has proved of double value to the cause of geological 

 science, inasmuch as it has led to the above remarks from 

 this great Grerman master of petrology. 



