'2 SUPPLEMENTARY NOTE ON LIMURITE IN TASMANIA. 



granite area to the west is shown by the tourmaline and 

 axinite jnst alluded to, and if these vapours extended to 

 the pyroxenic magma at the Colebrook, and were carried 

 up with it, the origin of the iimurite rock would be ac- 

 counted for. Last year a Note on Datholite was submitted 

 by Mr. AV. F. Petterd, and now the authors state the results 

 of a microscopical examination of this mineral. Another 

 new mineral is added to the list of the components of this 

 singular rock, viz., the boro-calcium silicate, danburite, and 

 its microscopical characters are enumerated. A further 

 mineral with characters suggestive of its being a precipitate 

 from a boric solution is mentioned. It is somewlaat similar 

 to the decomposition product of boracite known as parasite, 

 a hydrous magnesian borate. The authors consider that 

 the Iimurite rock throws light on the question of the age 

 of the granite on the West Coast, as the Colebrook intru- 

 sion appears to be younger than the serpentinous and 

 gabbroid rocks to the west of the mine. 



