624 



Transactions. 



(4.) Economic Deposits in the Older Igneous Rocks. — A few vein? of rusty 

 calcite and of quartz pseudomorphic after pyrite were noted m igneous 

 rocks near Kerr Point. An assay of a sample from these veins yielded — 



Gold .. Idwt. 21gr. ) ^. , ^ n a;i 



Silver .. „ 15 „ f ^^lueperton .. 7s. 6d. 



In tlie same locality bands ricli in pyrite and containing some chalcopyxite 

 also occur. These were examined for gold, silver, copper, cobalt, and 

 nickel, but yielded only — 



Silver . . . . . . . . 7 dwt. 13 gr. per ton. 



Copper . . . . . . . . 6-24 per cent. 



The surface of the high land forming the North Cape Promontory is 

 strewn with blocks of hydrous ferric oxide derived from the decomposition 

 of the underlying basic rocks. An analysis of this is subjoined, which is 

 interesting as showing the high percentage of chromic oxide — probably 

 derived from the chromite of the ultra-basic rocks : — 



Silica (SiOs) 

 Alumina (AUOg) 

 Ferric oxide* (FeoOg) 

 Manganous oxide (MnO) 

 Lime (CaO) 

 Magnesia (MgO) 

 Chromic oxide (CrgOg) 

 Loss on ignition 

 Undetermined . . 



* Equivalent lo metallic iron 48-35 per rent. 



2-89 

 7-69 



69-07 



0-10 



Nil 



0-60 



3-25 



16-01 

 0-39 



100-00 



Dr. Maclaurin. the Dominion Analyst, adds the following note : " On 

 heating, the sample gives a colour similar to that of Parapara iron-ore 

 when burnt, and therefore should be suitable for paint." 



EXPLANATION OF PLATES LII-LVII. 

 Plate LIL 

 Map of the northernmost portion of New Zealand. 



Plate LIII. 

 Fig. L Sand-dunes on sea-coast near Te Paki. 

 Fig. 2. " Bad Lands " topography, Rahia Bay. 



Plate LIV. 



Fig. L Spirits Bay, from Whangakea end. 

 Fig. 2. Rock bench at Cape Maria van Diemen. 



Plate LV. 

 Fig. \. Boundary between sand-dunes and Older Debris near Te Paki. Shows ponds 



formed by clogging action of advancing sand. 

 Pig. 2. Advancing sand near Cape IMaria van Diemen. The scrub-covered hill is an 



outcrop of the Older Debris nearly overwhelmed by the sand. 



Plate LVL 



Fig. L Andesite breccia from near Coal Point. 



Fig. 2. Basalt from Whangakea, west end of Spirits Baj'. 



Fig. 3. Norite from north end of Wharekau Bay. 



Plate LVII. 

 Fig. L Lherzolite from mainland just inside North Cape Island. 

 Fig. 2. Diopside-sphene band cutting the rock shown in fig. \. 



