202 



hardly be any doubt, that the spodumene-modification, which is 

 deposited from the liquid mass, is quite the same as that, which is 

 discerned by us as |?-spodumene. There are no reasons to adopt the 

 existence of a third modification, which on cooling shonld be con- 

 verted into the fi-form, as occasionally has been done. 



§ 15. Before describing our experiments with this compound with 

 respect to the study of the transformations into the solid state, the 

 determined vahies are once more recapitulated in the following table. 



From this table (next page) we can see, that iii i/eiieral the melting- 

 temperntures of the natural hmzites are considerably higher than those 

 for the synthetical products, and further we can, generally speaking, 

 deduce, that the meltingpoint of the l^unzites are decreasing at the same 

 time ivith the increase of specific gravity. (The specific gravities of the two 

 first mentioned kunzites ditfer too little to give any certain argument 

 for this view). Of the two kinds of dense spodnmenes however, the 

 mineral of higher specific density seems to have the higher melting- 

 point also, although in this case the meltingpoints are too close 

 together, and are moreover not snfficiently sharp, to give any certain 

 argument for an eventual rational relation between (he two mentioned 

 constants. 



§ 16. Now we will proceed to the question, in what relation 

 the dilferent modifications of the compound LiAlSi^O, stand with 

 respect to each other. That there are several of these modifications, 

 can already be deduced from the mere fact, that the product oj 

 solidification of the natural spodumenes is quite different from, the 

 original substances. 



Our investigations moreover have taught us, that there are really 

 only two modifications, which can be discerned as n- and ^-spodumene. 

 Of these two forms the /?-modification is undoubtedly the one to be 

 considered as the more stable form at temperatures in the immediate 

 vicinity of the meltingpoint. The question, however, then rises im- 

 mediately : in what relation are u- and /?-spodumene to each other? 

 Are they enantiotropic foi-ms, like e.g. wollastonite and pseudo-wollasto- 

 nite? Or arc they monotropic modifications, as e.g. they are observed 

 in some forms of the pentamorphic magnesiummetasilicate ? 



After numerous experiments in this direction, we have come to 

 the opinion that both forms of spodumene must be considered as 

 monotropic ones with respect to each otiier, and a-spodumene, i.e. all 

 kunzites, hiddenifes, spodumenes of nature, must be metastable phases 

 of lite compound with respect to the (i-form at all temperatures below 



