272 



WASHINGTON: ITALITE 



just described, both megascopically and microscopically, the 

 leucite crystals being almost identical. Small crystals of greenish, 

 non-pleochroic augite are, however, more abundant, and there is 

 considerable melilite, in thickly tabular crystals interstitial 

 between the leucites and in cavities in the specimen. The rock 

 contains no glass, the melilite taking its place, and neither garnet, 

 biotite, nor olivine is present. The rock contains about 65 per 

 cent of leucite, 18 of melilite, 20 of pyroxene, and 2 of magnetite. 

 An analysis gave the results shown in table 2. 



TABLE 2 

 Analysis of Vesbite 



Si02 45 49 



AI2O3. 



FeoOs. 



FeO.. 



MgO. 



CaO. 



NajO. 



K2O. . 



17.66 

 0.81 



1-45 



4.27 



16.72 



1.66 



11.44 



H.2O+ 0.93 



HaO" o . 05 



Ti02 0.13 



P2O5 0.16 



SO3 None 



CI 0.03 



MnO Trace 



100.80 



This rock is essentially a melilite italite, and the name of 

 vesbite (from a Latin name of Vesuvius) is given it. Vesbite is 

 intermediate between italite and venanzite, and is also related to 

 the melilite leucitites or cecilites, to use an old name of Cordier 

 for them. It falls in the position II. 9. 2. 2, of the quantitative 

 classification, and the name vesbose is given to this subrang. 



