25? 



After being melted liowever, the rcddishbrowii, crystalline pi'odnct 

 had a specific gravity at 25",] C. : ^/40=2,4(>3, while the refractive 

 indices of the feebl}' birefriiigent grains were found to be about 

 1,522 and 1,527. There is no doubt whatever about the fact, that 

 the solidified product is again a modification absolutely different from 

 the original kunzite ; moreover it is evidently identical with the 

 already mentioned /?-spodumene. 



IV. Hiddenite from Alexander CounUj, North Carolina, U.S.A. 



Long, needle-shaped, pale green crystals, and emerald-green crystal- 

 fragments, which are transparent and dichroilic. The specific gravity 

 of this mineral at 25°, 1 C. was found to be: (/4U = 3,295 ± U,Ü02 ; 

 the refractive indices were: /2i = 1,664 and y^, = 1,674. The data 

 for the specific density, given in literature, vary between 3,152 and 

 3,189. Of a hiddenite from Aled-ander City, with specific weight 

 of: (/4ü= 3,177, the analysis gave the following results: 



SiO, : 63,95 7,, FeO : 1,1 7, 



Al,0,: 26,58 7„ JSTa^O: 1,54 7, 



Li,0 : 6,82 7, CaO -. no trace. 



The sum of the principal constituents is here 97,35 7o l f^ie hue 

 of the crystals is caused by the admixture of i^dO, which is oxydized 

 in melting to Fe.J)^, giving a brownish-black or chocolate-brown 

 colour to the solidified mass. Another hiddenite of the same locality, 

 but of a paler colour, had: 64,357, .§/(>.„ 28,107, .4/, C>3, and 7,057„ 

 LiJJ, — consequently together: 99,5 7,; moreo\er: 0,25 7o l^^C 

 and only about 0,'è'' 1^ Na.fi. The differences of the meltingpoints 

 of these two kinds of hiddenite, were about 1° C. or less. In a 

 series of observations, made with thermoelement IV, the melting- 

 point was found at 14565 M. V. ± 10 M. V. ; after correction, this 

 coiTes[)onds to 1418^ ±1°C. ^G.Th.). On cooling down the molten 

 mass, first an undercooling is observed to r.bout 1255° C, if the 

 temperature-fall was about 4° })ro minute; then the temperature 

 rose to 1262° 0. during the solidification of the mass, being 150^0. 

 lower than the real equilibrium-temperature. 



Another time we found an undercooling to 1208^0., then 

 solidification at 1214° C, — this being 204° C. lower than the true 

 meltingpoint 1 Although this point of solidification is lower than that 

 for the pure kunzites, it can liave no essential signification whatever, 

 being wholly dependent on the speed of cooling and other accidental 

 circumstances. 



