146 THE MINERALS OF TASMANIA. 



Respecting this substance, Mr. Sticht remarks : — 

 " Judging from the analysis mentioned below, there might 

 be slight traces of alkalies present, but these would have 

 no special bearing on the composition otherwise." It 

 occurs at the 850-feet level, associated with the quartzite 

 schist, and in connection with a 15-inch seam of chalco- 

 pyrite, 15 feet from the conglomerate or the contact of the 

 same with the schist. 



At the 700-feet level of the same mine a variety of this 

 mineral is found close to the conglomerate. It occurs 

 as a finely-divided aggregate of scales of a pale yellowish- 

 green colour, with a semi-metallic sheen. It is much less 

 compact than the one above referred to. 



The analysis shows the following composition : — 



Per cent. 



Silica = 60-20 



Alumina = 31-90 



Potassium oxide = 0*20 



Sodium oxide = 0-07 



Magnesium r= nil 



Lime = nil 

 Ignition loss, i.e., 



combined water = 7-50 



99-87 



At the Lyeli Company's Chester Pyrites Mine, in the 

 North Pieman district, the mineral occurs in considerable 

 quantity; in fact, it forms the great bulk of the country- 

 rock in which the pyrites is contained. At times it con- 

 stitutes veins in the solid pyrites. It is composed of small 

 white scales with a distinctly silvery sheen. Apparently 

 it has partly undergone kaolinisation, and this may 

 account for the slight divergence in composition from the 

 normal type. This alteration is shown by the analysis, 

 which is as follows: — 



100-1 

 Sjiecific gravity = 2-78. 



It would appear that this almost compact to scaly 

 granular pyrophyllite forms the base of some of the 



