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LXIV. On Rhabdophane, a new Mineral. 

 By W. G. Lettsom, Esq.* 



HAVING ascertained from Monsieur Lecoq de Boisbau- 

 dran, who had had the kindness to favour me with a 

 specimen of his new metal gallium, that it would he agreeable 

 to him to examine our British blendes for that metal, I applied 

 to various dealers for specimens thereof, and I also asked a 

 few friends to give me their assistance in the matter. Among 

 the latter was Mr. Ludlam, who with his usual liberality sent 

 me three or four specimens. 



Among them was one which in its appearance differed from 

 any British blende that I am familiar with. It was in small 

 mamillated globules, brown, with a peculiar greasy lustre. 

 Having a suspicion that possibly it might not be a blende, I 

 submitted it for examination to that Grand Inquisitor the spec- 

 troscope. 



Letting a bright light fall on the specimen, I looked at it 

 with a pocket-spectroscope, when immediately the bands due 

 to the presence of didymium became apparent. I had thus 

 come across what, at least, was no ordinary blende. 



Having submitted the specimen to Mr. Maskelyne, that 

 gentleman was so good as to cause a preliminary chemical 

 examination of the mineral to be made, from which it appears 

 that it contains neither zinc nor sulphur, and is consequently 

 no blende, but that it is essentially a phosphate of didymium. 



With some pure fragments of the mineral which I have 

 placed in the skilful hands of Mr. Walter Noel Hartley, that 

 gentleman has kindly undertaken to make a complete analysis f 



* Communicated by the Crystallological Society, having been read 

 November 23, 1878. 



[This paper was withheld from publication with the intention that it 

 and the analysis should appear simultaneously. Through some misap- 

 prehension this intention has not been carried out, and the analysis has 

 already appeared in the Journal of the Chemical Society for May. — Sec. 

 Cryst. Soc] 



t [Professor Hartley's analysis shows it to be a hydrated phosphate of 

 cerium, didymium, and yttrium, capable of representation by the formula 

 R 2 3 . P 2 5 . 2H 2 0, the percentage composition found being : — 



Combined water 7-97 



P 2 5 26-26 



Ce 2 3 ,Di 2 3 ,Yt 2 3 .. 65-75 



Ce 2 3 : Di 2 3 : Yt 2 3 = 23-19 : 34-77 : 2-39 nearly. 



This seems to be the first time that yttrium has been found in a British 

 mineral.] 



