LiVERSiDGE. — On some of the N. Z. Minerals in the Otago Museum. 499 



The mica was not perfectly pure ; it was found difficult to separate it 

 completely from the other constituents of the rock ; the difficulty was 

 mainly due to the smallness of the quantity at my disposal. 



Alkalies in Felspar (Albite). 

 Potash .. .. .. .. .. 1-071 



Soda .... .. .. .. 5-590 



6-661 per cent. (Liversidge). 



Garnet. — Breaksea Sound. 



An embedded crystal (the rhombic dodecahedron) broken across. The 

 matrix is syenite, having the wavy foliated structm-e of gneiss. Imme- 

 diately around the garnet the hornblende is almost entirely absent, which 

 causes that part of the matrix to be much lighter in colour, and conse- 

 quently the garnet is shown up to much greater advantage. 



It is highly probable that the hornblende and garnet are not very 

 dissimilar in chemical composition, and that when the rock underwent 

 metamorphism, and its constituents were free to re-arrange themselves, 

 the garnet " nucleus," or centre of crystallization, had the power to abstract 

 and build up certain of the rock constituents which would have other- 

 wise assumed the form of hornblende. Hence the probable reason of 

 the absence of hornblende in the immediate neighbourhood of the garnet. 

 It would be very interesting to put this suggestion to the proof by chemical 

 analysis, should additional specimens be obtainable. 



Limestone.* — Crooked Arm, West Coast. — (Labelled " Cipillino.") 



A white saccharoid limestone or marble, containing small crystals of 

 brown mica, a little quartz, and a few scales of graphite. 



The variety of marble known as cipillino contains talc or chlorite, hence 

 it is marked by green-coloured streaks and veins. 



This specimen cannot therefore be classified with it. 



Analysis. 

 Carbonic acid . . . . . . . . . . 38-284 



Iron sesquioxide and alumina 



Lime 



Magnesia 



Mica, silica, etc, insoluble in acid 



Undetermined constituents 



1-253 



48-269 



-402 



9-459 



2-333 



100-000 (Liversidge). 



Halloysite.j — Water of Leith, Dunedin. 

 An opaque white earthy substauce, soft and soapy ; associated with it is 

 a httle black halloysite ; when immersed in water it gives off air bubbles 



* Keport West Coast Expedition, Otago Gazette, 1863, 459. 

 t Eep. N.Z. Exb., 1865, 438. 



