Page:Transactions NZ Institute Volume 15.djvu/488

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black shales of the Awanui series at Poverty Bay; Mr. Skey (Goel. Rep., 1870–71, p. 88) mentions its occurrence at the Thames; Dr. v. Haast (Geol. Rep., 1873–74, p. 18) as crystals in dark greyish sands at Lake Heron; and Mr. McKay (Geol. Rep., 1880–81), at Waihao River, Canterbury.

Professor Liversidge (Trans. N.Z. Inst., vol. x., p. 493) has described some rough crystals from Moeraki and Awamoko, and thin, columnar, opaque white crystals, sometimes interlacing and somewhat fibrous, from White Island, as well as a white opaque mammillated encrusting mass from a cave at Mr. Nicholas', Lake Wakatipu.

Besides these, specimens have been forwarded for identification from the Malvern Hills by Mr. H. H. de Bourbel, from the Kaitoki Ranges, New Plymouth, by Mr. Robert Hughes, and the Thames by Mr. McDonald. The specimens in the Colonial Museum are chiefly from White Island (from which locality a very beautiful collection has been made by Dr. Hector), and from Waihao, Canterbury.

Dr. Hector has described those from White Island as follows (Trans. N.Z. Inst., vol. iii., p. 284):—"The specimens obtained from the edge of the lake are chiefly masses of sulphate of lime, sometimes in the form of massive gypsum, but more frequently crystallized in the form of oblique prisms of selenite. The faces of these crystals are frequently coated with crystalline films of pure sulphur."

The specimens from Waihao are transparent crystals of selenite roughly crystallized and imbedded in clay-shale.

They occur chiefly as crystals, consisting of the prism ∞P., the clinopinacoid ∞P^c∞, and the hemipyramid -P; and they are frequently macled, along a face parallel to the orthodiagonal, to form rough arrow-head crystals, sometimes of considerable size. They are sometimes arranged in stellate groups.

A specimen has also been collected from Tohatapu, in the Otamatea arm of Kaipara Harbour, where it occurs as opaque white plates imbedded in a sandy marl.

Apatite, 3 Ċa3 (symbol characters) + Ca (Cl, F).—This mineral is mentioned by R. Daintree, Esq., F.G.S. (Trans. N.Z. Inst., vol. vii., p. 459), as slender acicular crystals occurring in dolerite from the Hororata district, and as long prisms in dolerite from the Acheron section.

Salts of Magnesia.

Magnesite, Ṁg C̈.—A soft, white, earthy variety of this mineral is in the collection of the geological survey from Rotorua, and a nearly pure, white, massive form has also been collected by Mr. S. P. Smith from the Chatham Islands. In 1878 I collected a crystallized specimen from Collingwood, in which the rhombohedral cleavage is very perfect, colour white, lustre pearly.