Page:Transactions NZ Institute Volume 15.djvu/506

intersected by numerous small white veins. Readily decomposed by H. Cl. at a temperature of 212° Fah.; lost 13 per cent. water, but as it is very probable this is in greater part or altogether constitutional along with that requiring a higher temperature for its expulsion, the whole of the water present in the stone is entered in the appended analysis under one head:—

Schrötterite, …Al² S̈i + 8 Ḣ.—Professor Liversidge (Trans. N.Z. Inst., vol. x., p. 500) mentions a mineral from the Malvern Hills, Canterbury, which is probably schrötterite. His description is as follows:—"In rounded wax-like masses, filling the cavities of an amygdaloidal trachyte (?) rock, and has a mammillated incrustation upon its surface; green, grey, and white; hardness about 3.5; streak, white; rather tough; breaks into more or less conchoidal flakes; translucent; waxy lustre. Before the blowpipe it becomes white and opaque and much harder, intumesces slightly and tinges the flame green; affords deep blue when ignited with cobalt nitrate; does not gelatinize with hydrochloric acid, but granular silica is thrown down; gives off much water when heated in a closed tube.'

Pimelite, 2 …Al S̈i + 3 Ṁg S̈i + 10 Ḣ.—The occurrence of this mineral filling cavities in amygdaloidal rocks, at Malvern Hills, Clent Hills, etc., is mentioned by Dr. v. Haast (Jurors' Rep. N.Z. Ex., 1865, p. 257).

Idocrase (Vesuvianite), 3 (Ċa, Ṁg)³ S̈i + 2 …Al S̈i².—This mineral occurs as dirty green, fluted, prismatic crystals, in quartz associated with the crystalline rocks of Dusky Sound; specimens having been forwarded by Mr. W. Docherty. The larger crystals have a resinous lustre and the smaller ones, which are of a brighter green, are more pellucid.

Epidote, 2 (…Al, …Fe) S̈i³ + 3 Ċa S̈i.—The occurrence of this mineral in gneiss granite and granulite of the West Coast is mentioned by Dr. Hector (Jurors' Rep. N.Z. Ex., 1865, p. 266) and by Dr. v. Haast in the diorites of Mt. Torlesse range (Jurors' Rep. N.Z. Ex., 1865, p. 257) and in the melaphyres of the Mt. Somers district (Geol. Rep., 1873–74, p. 9). A massive form from Wairarapa, Wellington, of a greenish-grey colour, is also in the collection of the Colonial Museum. Before the blowpipe it