286 BERNARD F. DAVIS. 



Occurrence of GADOLINITE in WEST AUSTRALIA. 



By Bernard P. Davis, b.sc, 



With notes by W. G. Woolnough, b.sc, f.g.s., and Prof. 

 T. W. Edgworth David, b.a., f.r.s. 



[Read before the Royal Society of N. S. Wales, October 8, 1902.'] 



Introduction. — The mineral described by Mr. Davis in 

 the accompanying paper was obtained by him at Coogle- 

 gong, in the Pilbarra District, West Australia. He sub- 

 mitted it in April, 1901, to Mr. W. G. Woolnough, b.sc, and 

 myself for a preliminary examination. Its general appear- 

 ance at first suggested that it was allanite, but a blowpipe 

 examination of the mineral by Mr. Woolnough showed that 

 it was either gadolinite or some very closely allied mineral. 

 Mr. Davis took the mineral with him to England, promising 

 to analyse it, and send the analysis for publication in our 

 Proceedings. The analysis reached me at the end of last 

 year, but too late for the 1901 session of our Society. 1 



Mode of occurrence. — "Dr.Bonney very kindly examined 

 the rock specimens which I brought home from the same 

 district in which these minerals occur. They were gneisses 

 and granites of marked archsean type. Field evidence 

 showed that a more acid granitic rock, usually very coarsely 

 crystalline, had intruded the gneiss, sometimes breaking 

 across the planes of foliation without disturbing their 

 direction, and by working along the planes of foliation 

 becoming absorbed into the structure of the gneiss. In 

 fact one had the process of gneiss-making before one. 



"Dr. Bonney thought that the granitic intrusion was pro- 

 ably very little later than the original gneiss. The lodes 



1 The portions of this paper in quotation marks are taken from the 

 letter from Mr. Davis. 



