^^^' 55'] EHYOLITES OF THE HAURAKl GOLD FIELDS. 469 



of felspar-glass through secondary heating. They appear dark in all 

 azimuths between crossed nicols. The spherulites and axiolites which 

 constitute the enclosing rhyolite have also been rendered isotropic 

 through the same cause. X 75. Ordinary light. (See p. 400.) 

 Fig. 3. Hg [6J Omaha. — Ehyolite, showing portions of the arms of a micro- 

 felslte-spherulite traversed by fluxion-streaks. X 30. Ordinary light. 

 (See p. 455.) 



4. H^ [181] Waihi. — Fused edge of a section of a fragment of spherulitic 



rhyolite, containing isotropic crystals of felspar and brown microfelsite- 

 spberulites. Part of the fragment is shown on the left of the field, 

 containing a porphyritic crystal of felspar, which has been rendered 

 isotropic by secondary fusion. The brownish glass resulting from the 

 superficial fusion of the fragment is seen to have run in irregular 

 threads, which have mingled with the surrounding colourless glass of 

 the enveloping rhyolite. X 30. Ordinary light. (See p. 459.) 



5. Hi- Omahu. — Spherulitic rhyolite, the spherulitic bauds includiag 



patches consisting of quartz with crystals of felspar (sanidine and 

 oligoclase) and small octahedra of magnetite. X 30. Ordinary light, 

 (See p, 451.) 



6. Hg [176j Pumice-tuff, Waikino, near Waihi. — The figure shows frag- 



ments of pumice, the steam-pores in one fragment following a direction 

 different from those in another. X 75. Ordinary light. (See p. 457.) 



Discussion. 



The Kev. J. F. Blake said that he was much interested in the 

 rocks last-mentioned by Mr. Eutlej, namely, mushroom-like masses 

 of quartz-rock, which reminded him of the quartz-knobs of Anglesey; 

 also the silicified andesites, which recalled the rock of Treifgarn. 

 He hoped that further particulars of these rocks would be forth- 

 coming. 



Mr. J&UTLBr briefly replied to the previous speaker's remarks, and 

 stated that he hoped at no very distant period to examine additional 

 specimens of Hauraki rocks which had been affected by solfataric 

 action. 



