'^59 



like porcelain, with predominant cleavage. The carefnlly selected 

 material was finely pulverized, and investigated as described l)ofbre. 

 The specific gravity at 25M C. was: ^/..o = 3,154 ± 0,002 ; the 

 refractive indices were about : ii^ = 1,65G and a, =r 1,672. A micro- 

 photograph of it between crossed nicols is reproduced in the fig. 13. 



The meltingpoint was determined several times with tlie thermo- 

 element III; the following results were obtained : 14669 =t 13 M.V., 

 being after correction : 1427^ ± 1° C. on the gasthermometer. Also 

 in this case the meltingpoint is not quite so sharp as with the kun- 

 zites, just because of tiie chemical inhomogeneity of tlie material. 



The obtained product liad a specific gravity : r/40 = 2,336 at 25°,4 C; 

 the weakly birefringent, irregularly extinguishing scales, had refractive 

 indices of about: 1,517 and 1,520; tlie birefringence is not greater 

 than : 0,003. 



In fig. 8 a rnicrophotograph between crossed nicols is given of 

 the dense «-spodumene of Maine ; in fig. 9 the same preparation, 

 molten and solidified into the /?-form is reproduced in the same way. 

 The strong analogy with the image of fig. 4, representing an arti- 

 ficial /?-spodumene, made from LiAlO., and LiO^, is obvious. 



Another preparation was not melted, but only kept at a constant 

 temperature of about 1200° C. for some hours. The original «-form 

 appeared to be totally converted into /?-spodumene ; the volume of 

 the mass had increased then in such a degree, that the platinum- 



Fig. S. 

 Dense a-Spodumene of Maine, between crossed 



Nicols. 



Fig. U. 



^-Spodumene obtained by melting and crystallization 



of the ^.-modification (X Nicols). 



