103 



On the Analysis o/Euclase. By J. W. MALLET, Esq., Ph. D. 



Euclase, from its transparency, delicate shades of colour, 

 and perfect crystallization, is one of the most beautiful mineral 

 species with which we are acquainted ; and since it is at the 

 same time a mineral of great rarity, good specimens of it 

 form some of the most highly prized ornaments of mineralo- 

 gical collections. 



Such of the characters of the mineral as can be examined 

 ■without injury to the specimens, have been pretty accurately 

 studied, especially the complex crystalline forms under which 

 it occurs, which have been described at length by Hauy, 

 Weiss, Phillips, and Levy. Our knowledge of its chemical 

 composition, however, the investigation of which involves the 

 destruction of the specimens operated on, depends upon a 

 single analysis by Berzelius, as the number given by Vau- 

 quelin, the only other chemist who has examined the sub- 

 stance, are almost valueless, presenting a loss of about 30 

 per cent. 



Though from the high authority of Berzelius as an analyst, 

 any other investigation could scarcely be expected to yield 

 results of much novelty, or differing materially from those he 

 has given, yet a second analysis possesses some interest, even 

 if merely confirmatory of his. The results of one which 

 I have recently made, I wish, therefore, to bring under the 

 notice of the Society. 



The material employed for this analysis, consisted of four 

 fragments of crystals, weighing together about 20 grains. 

 Though this is rather a smaller quantity than is usually 

 taken for a mineral analysis, it was in the present case quite 

 enough, as the constituents to be determined were but few, 

 and alumina and glucina form a large proportion of the 

 whole. These fragments were perfectly clear and transpa- 

 rent, three of them of a beautiful pale mountain-green, and 

 one of a very light tinge of blue. They presented both na- 

 tural crystal planes and faces of cleavage, and amongst the 

 former were several adapted to the use of the reflecting go- 



