Skey and McKay. — On Minerals from Stewart Island. 415 



Art. XLIX. — On certain Bare Minerals associated with 

 the Tin-ore of Steivart Island, 



By William Skey, Analyst to the Geological Survey of 



New Zealand. 



WitJi Notes on their Mode of Occurrence. By Alexander 



McKay. 



[Read before the Wellington Philosopliical Society, 10th 'July, 1889.] 



Towards the end of last Mai-ch a large and valuable collection 

 was submitted to me for examination. It comprised numerous 

 minerals and specimens of rock-masses which were collected 

 by Mr. McKay, during his recent survey of Stewart Island, 

 from the stanniferous deposits and other rock-formations of 

 the island. 



The results of my investigations I briefly communicated 

 from time to time, as obtained, to the Director of the Geo- 

 logical Survey ; but, as there are many interesting points in 

 connection therewith which have not been treated of in those 

 communications, and which should be made public, I have 

 thought it proper to address myself to this Society in a paper 

 which shall deal with the whole subject. 



The following are the full particulars of the results of my 

 investigations of Mr. McKay's collection to date. The precise 

 localities of the minerals that I shall describe, and certain 

 interesting particulars as to their mode of occurrence, will be 

 given as a sequel to this paper by the collector of the speci- 

 mens : — 



Beryl (Silicate of Alumina and Glucina). — This mineral as 

 exhibited to me is in broken crystals belonging to the hex- 

 a,gonal system. Their cleavage is obviously basal. The dia- 

 meter of the largest crystal is l-|in., and the length of the 

 fragment in the direction of the longest axis is l^in. Colour, 

 pale-green ; subtranslucent ; hardness, 8. 



Fhior-spar (Fluoride of Calcium) . — • Highly crystalline ; 

 crystals derived from the cube. Colour generally pale-green ; 

 some parts colourless. The coloured parts exhibited vivid 

 phosphorescence when gently heated. 



Analysis. 



Fluorine . . . . . . . . . . 48-12 



Calcium . . . . . . . . . . 51-19 



Loss (impurities) . . . . . . 0-69 



10000 

 ToxivDMline (Silico-borate of Alumina).— This specimen was 

 handed to me by the collector as tourmaline, and it proved to 

 be the ferruginous variety. It is black in mass, light-brown 

 in powder. Occurs as columnar aggregations in quartz. 



