LARSEN AND SCHALLER: CEBOLLITE 



481 



Chemical properties. The material selected for analysis repre- 

 sented the completely altered melilite and consisted mainly of 

 ceboUite but contained considerable garnet, diopside, and vesu- 

 vianite so intimately admixed that separation was found impossi- 

 ble. The analysis made by W. T. Schaller in the laboratory of 

 the U. S. Geological Survey is given below in Column 1. In- 

 Column 2 the analysis is computed free from the insoluble por- 

 tion which represents diopside, garnet, etc. In Column 3 the 

 analysis of the fresh melilite is given for comparison. 



Analysis of Cebollite 

 By W. T. Schaller 



1. Cebollite from 0.6 of a mile south of the forks of Beaver Creek, Gunnison 

 County, Colo. 



2. Analysis computed free from insoluble portion, diopside, garnet, vesu- 

 vianite, etc. 



3. Melilite from Beaver Creek, Gunnison County, Colo. 



The formula derived from the analysis is 3SiO2.AloO3.5RO. 

 2H2O, in which R is chiefly Ca with smaller amounts of Mg, 

 Nao, and Fe. The ratio of NasO : MgO -|- FeO : Ca is about 

 1:3: 16. Cofisidering all the RO as CaO, the formula of cebol- 

 lite, H4 Al2Ca5Si30i6 may be written in two ways, as follows: 



1 (Si04)3.Ca5.[Al(OH)2]2. 



2 (8104)3. (GaOH)4.Ca.Al2. 



