258 



T^. SpoduDhme. of Somerl), Finland. 



A white, opaque ciyptocrysfiillirie and verv hard mass. It was 

 iiiiely ground, and investigated in a manner, quite analogous to that foi'- 

 nierly described. The specific gravity at 25°,1 C. was : r/4(. ^ 2,997 ± 

 0.050 ; tiie refractive indices were about : n, = 1 ,658 and n^ = 1,669. 

 With the thermoelement IV the meltingpoint was found at 14649 

 M.V. ±5 M.V. ; being, after correction, 1425° C. on the gasthermo- 

 nieter. i^ccause of the in homogeneity of the material, the meltingpoint 

 is here not so sharply localized on the heatingcurves, as in the 

 cases of the kujizites ; on cooling the molten mass, solidification 

 occurs in the neighbourhood of 1298^ C. 



The substance solidified and heated for some hours below its 

 meltingpoint, had a specific gravity at 25°, 1 C. of: r/40= 2,398 ; the 

 refractive indices were about: 1,510 and 1,518 for sodiumlight, 

 — just a little smaller than commonly with the /?-spodumene. The 

 substance always shows very complicated aggregations of feebly 

 extinguishing scales with undulatorj' e.xtinction. 



If the original substance is not melted, but only heated during a 

 longer lime below its meltingpoint, the crystals are converted into 

 the aggregations of the /3-spodumene ; the specific gravity at 25°,1 C. 

 was now: (/40=: 2,412 and the refractive indices about: 1,519. 



VI. Spodumene from Maine, U.S.A. ; perhaps from Wlndhain. 

 This mineral consists of long, opaque, prismatic crystals, looking 



Fig. 13. 

 Dense «-Spodumene of Somerö, Finland. (X Nicols) 



