Cox. — On the Mineralogy of New Zealand. 40*7 



Oligoclase, 2 .jy. Si 3 + (Na, Ca) 2 Si 3 , is mentioned by Dr. v. Haast in 

 quartz porphyries of Mt. Misery and Malvern Hills (Jurors' Eep. N.Z. Ex., 

 1865, p. 257), and E. Daintree, Esq., F.G.S. (Trans. N.Z. Inst., vol. vii., 

 p. 458), mentions the occurrence of a plagioclase felspar, which is probably 

 oligoclase, in granite from Snowy Peak Kange. 



Obsidian is mentioned, by Dr. v. Hochstetter, with rhyolites in the 

 Taupo district (New Zealand, Eng. ed., p. 407) ; by Dr. v. Haast, on the 

 sides of trachytic dykes (selbands) in Banks Peninsula (Jurors' Rep. N.Z. 

 Ex., 1865, p. 257, and Trans. N.Z. Inst., vol. xi., p. 504) ; aud by Mr. 

 J. A. Pond, in the volcanic rock from Mr. Firth's well near Mt. Eden, 

 Auckland (Trans. N.Z. Inst., vol. vii., p. 406). Its distribution in the 

 North Island is widespead in the volcanic regions which occupy the central 

 and north-east portions of the island ; but, so far as I am aware, no solid 

 floes have been discovered, and the mineral has only been found in isolated 

 blocks. It was formerly largely employed by the Maoris for the manufac- 

 ture of weapons and implements. There are several specimens in the 

 collection of tbe Colonial Museum from Taupo and White Island. 



Pumice. — Is found throughout the volcanic region of the central portion 

 of the North Island whence it is brought down to the sea by rivers, and 

 distributed along the coast by the action of the tides and currents. It is 

 mentioned by Dr. v. Hochstetter (New Zealand, Eng. ed., p. 43) as 

 occurring in plateaux round Lake Taupo, 2,000 feet above the sea and 

 he states (p. 384) that Mr. Grace's house is built of it. It is mentioned 

 (Jurors' Eep. N.Z. Ex., 1865, pp. 35, 253) from the beach near Napier, 

 where it is found in considerable quantities, brought doAvn by the rivers 

 from the north and also from Waikato, and Mr. J. C. Crawford (Trans. 

 N.Z. Inst,, vol. vi., p. 356) states that it occurs in large quantities at 

 Tokano and (Trans. N.Z. Inst., vol. viii., p. 377) that pumice floats down 

 the Wanganui River in such quantities that it would be easy for a ship, 

 anchored in the river, to put out nets and so load the ship. Around the 

 volcanic group of Ruapehu aud Tongariro there are immense areas covered 

 with pumice, and at Kereru, Napier, and many other localities on the east 

 coast of the North Island, there are extensive deposits of compact white 

 pumice-sand, which are mentioned by Mr. McKay (Geol. Eep., 1876-77, 

 p. 81). 



Pitchstone. — The only district in New Zealand where this mineral occurs 

 is between Mt. Somers and Snowy Peak, where it is associated with quartz 

 porphyries of which it appears to be the vitreous form, a complete series repre- 

 senting the change from a fluid pitchstone, through various stages, to a 

 quartz porphyry with felsitic base and small crystals of quartz and garnet 

 in which no fluxion structure is visible. It is of all colours, from grey to 



