46 H. S. Washington — New Leucite Rock. 



erated, which would go to form leucite out of the kalio- 

 philite. The relations of norm and mode can, however, 

 be best studied after the melilite has been analysed, 

 which it is hoped to do soon. 



As to classification in the quantitative system, the 

 figures of the norm and of the analysis place this rock in 

 dosalane, in the perlenic order (but close to the border 

 of the feldolenic order), in the domalkalic rang, and the 

 dopotassic subrang. The position is indicated by the 

 symbol II ". (8) 9. (1) 2. "2. No rock has yet been found 

 that falls in this rang and subrang of lappare, and, 

 though it is transitional as regards order and rang, and 

 intermediate as to subrang, the rock is so unusual that 

 one may be permitted to violate one of the rules of 

 nomenclature and give a name based on this rock. That 

 which is suggested for the rang is vesbase, and that for 

 the subrang is vesbose, both derived from the name given 

 to the rock. 



It is clear that the rock has no exact analogue in the 

 prevailing systems of classification. Although it is 

 much like italite, it is so much higher in melilite and 

 pyroxene as to merit distinction from this, though it 

 might be designated as a melilite italite. It also resem- 

 bles the olivine-melilite-leucite venanzite of Sabatini 15 

 (euktolite of Eosenbusch), 16 but this contains so much 

 olivine, melilite, and pyroxene as to fall into dofemane. 

 Mineralogically, also, it resembles cecilite ("melilite leu- 

 citite"), but this contains much more augite and less 

 leucite, and is structurally much finer grained and other- 

 wise different. 



Though the rock is essentially a melilite italite, the 

 name vesbite 17 is suggested for it, meaning an effusive 

 rock (in this type rather coarse-grained), composed 

 essentially of 60-70 per cent of leucite, and about 20 per 

 cent each of augite and melilite. 



The chemical relations of vesbite to the salic italite on 

 the one hand, and to venanzite, cecilite (melilite leuci- 

 tite), albanite ("leucitite"), and missourite on the other, 

 all of these last rocks being distinctly femic, are shown 

 in the accompanying table. 



15 Sabatini, Boll. Com. Geol. Ital., 1898. 



16 Eosenbusch, Sb. Akad. Wiss. Berl., 1899, p. 110. Cf. this Journal, 7, 

 399, 1899 



17 This name is derived from Vesbius, a Latin variant name of Vesuvius. 



