Page:Transactions NZ Institute Volume 15.djvu/497

Augite, Ṙ S̈i = (Ċa, Ṁg, Ḟe) S̈i.—This mineral enters into the composition of all our basalts, dolerites, anamesites, trachydolerites, diabases, and melaphyres. Isolated crystals are rare, but there is a specimen in the collection of the Colonial Museum, of porphyritic diabase from Nelson, in which dark-green monoclinic crystals of augite are well developed, some of them being half an inch long. No macles are seen in this specimen.

It is mentioned by Dr. Hector in the basalts around Dunedin (Jurors' Rep. N.Z. Ex., 1865, pp. 266, 438), in basalt from the Snares, and in dolerite from Antipodes Island (Trans. N.Z. Inst., vol. ii., p. 179), and in the dolerites and basalts of the Auckland Islands (Trans. N.Z. Inst., vol. ii., p. 183); by Dr. v. Haast in trachydolerites and as fine twin crystals imbedded in agglomeratic tufa, Banks Peninsula (Jurors' Rep. N.Z. Ex., 1865, p. 257), in concretions in basaltic rocks of Chatham Islands (Trans. N.Z. Inst., vol. i., p. 180), and in basalts of Banks Peninsula (Trans. N.Z. Inst., vol. xi., p. 499); and by R. Daintree, Esq., F.G.S., in dolerite from the Selwyn River, Snowy Peak Range, Hororata District, Flagstaff Hill basin and Acheron section.

Asbestos.—The occurrence of this mineral at Milford Sound is mentioned by Dr. Hector (Jurors' Rep. N.Z. Ex., 1865, p. 266), and the late Mr. E. H. Davis records it from Dun Mountain (Geol. Rep., 1870–71, p. 112). There are several specimens in the collection of the Colonial Museum, but none of them possess that flexibility and readiness to separate into fibres without which the mineral is of but little value. The best sample was collected from Collingwood by Dr. Hector; it is of a pale green colour and fibrous. It occurs associated with the steatites there.

Tachylite, …Al S̈i² + 3 (Ḟe, Ċa, Ṁg, Ṁn, Ṅa, K̇) S̈i.—The occurrence of this mineral on the sides of fissures in the volcanic rocks of Banks Peninsula, where trachytic dykes have intruded, is mentioned by Dr. v. Haast (Trans. N.Z. Inst., vol. xi., p. 503).

Hornblende, Ṙ S̈i.—Is of very common occurrence in New Zealand as a constituent of the syenites, trachytes and diorites which abound, and also in certain hornblendic schists and gneiss which are met with in the northwestern part of the South Island, and again at the Bluff, Southland. It is mentioned by Dr. v. Hochstetter (New Zealand, 1863, Eng. ed., p. 471) as a blackish-green hornblende in the syenite of the boulder-bank, Nelson; by Dr. Hector as veins in syenitic and older trap-rocks in Milford Sound (Jurors' Rep. N.Z. Ex., 1865, pp. 267, 438), in the trachyte of the Sugar Loaves, Taranaki (Geol. Rep., 1866–67, p. 8), as a hornblende rock in the Auckland Islands and Ruapuke (Trans. N. Z. Inst., vol. ii., pp. 183, 185), and in diorite on Great Barrier Island (Trans. N.Z. Inst., vol. ii., p. 375); by Dr. v. Haast, in basaltic and doleritic rocks at Banks Peninsula, Malvern