■tT:: 



iiad Deen named Palla by the officers of the Geological Survej 

 Austria. Hector, Catalogue of the Colonial Museum, Wellingt 

 1870, p. 159, Nos. 19 and 20. Cox, Reports Geol. Expl. 187i 



PiTCnSTONE. 



Vitreous or sub-vitreous rocks with a more or less splint 

 fracture, and containing from two to eight per cent, of water. 



Jfakehi, Tauranya Co. — A dark brown, sub-vitreous rock, ( 

 taining fragments of other rocks. Section : vitreoi 

 brown and white, shewing fluxion, and containing minute fragments 

 of sanidine. 



May(rr Island— A reddish-brown compact rock, marbled with 

 yellowish- and greenish-brown ; lustre resinous. Section : Micro- 

 abundant felspar microlites shewing 

 vesicles are elongated and pass into trichites. (Plate 

 vui.,tig.2.) 



Spherulitic Pitchstone. 



Jiotorna, Tnuranga Co.— Black, lustre vitreous, containing grey 

 spherulites, often pink on the outside, up to -15 inch in diameter. 

 Section : Vitreous, with scattered belonites shewing fluxion, 

 elongated vesicles and trichites, in places almost pumiceous. Most 

 01 the trichites are straight, but others are curved or radiating 

 trom a centre which is often plainly a vesicle (Plate viii., fig. 3) ; 

 sometimes starting from a belonite ; some have rows of granules (1) 

 attached to one side. This rock plainly shews trichites to be 

 e ongated vesicles. There are also crystallites in tlie form of 

 globulites. Also a few very small crystals of (luartz, sanidine, 

 and plagioclase so that the rock passes in places into a rhyolite. 

 J-he spherulites all shew radiating structure and are brownish by 

 transmitted and white by reflected light. They are very opaque 

 put the small ones are translucent on their margins, and there the 

 interference cross is seen to be parallel to the nicol sections, 

 tsuaily, perhaps always, a small quartz crystal forms a centre 

 trora which, by reflected light, small black margarites are seen 

 radiating outwards on the white general mass. The sperulites 

 ^vere formed after fluxion movement had ceased. Perlitic cracks 

 re rare ; there are none round the spherulites. Hemo Gorge, 

 *iotorua. Hochstetter, New Zealand, p. 421 ; Thomas, Report 

 on Eruption of Tarawera, Wellington 1888, p. 16. 

 Obsidian. 



Vitreous rocks with conchoidal fracture, and containing less 

 than one per cent, of water. 



Mayor Idand—ma^ck. S.G. 2-3.5. Section: A nearly colourless 

 g ass with abundance of scattered crystallites and some microlites 



