AHT. 14. THE JADE OF THE TUXTLA STATUETTE WASHINGTON. 5 



optical study. iVfter pulverization the amount of material that was 

 available for chemical analyses was 0,8367 gram. The results of the 

 analysis are as follows, some analyses of other jadeites being given 

 in the Table 1 for comparison: 



Table 1. — Analyses of jadeites. 



1. Tuxtla Statuette. H. S. Washington, analyst. 



2. China. A, Damour, analjst. Bull. Soc. Min. France, vol. 4, p. 158, 1881. 



3. Val Susa, Piedmont. G. Aichino, analyst. S. Franchi, Boll. Com. Geol. Ital., 



1900, No. 2. 



4. Culebra, Costa Rica. F. W. Clarke, analyst. Clarke and Merrill, Proc. U. S. 



Nat. Mus., vol. 11, p. 125, 1888. 



5. Zaachita, Mexico. Clarke, analyst. Clarke and Merrill, Proc. U. S. Nat. Mus., 



vol. 11, p. 122, 1888. 



6. Tibet (?). H. W. Foote, analyst. S. L. Penfield in H. R. Bishop, Investigationa 



and Studies in Jade, vol. 1, p. 126, 1906. 

 la. Molecular numbers of 1. 



It is evident that the analysis of the jadeite of the Tuxtla statuette 

 differs notably from one of a purely sodic jadeite, such as No. 6.' 

 The Tuxtla mineral contains much less silica, alumina, and soda, but 

 more magnesia and lime. The absence of titanium, chromium (?), 

 and manganese is to be noted. The density of the Tuxtla material 

 is also markedly lower than that of sodic jadeite. 



From the chemical and optical characters, from the density, as 

 well as from the "exceptional homogeneity" of the Tuxtla jade, it 

 is evident that we have to do with a complex pyroxene, composed 

 of sodic jadeite in isomorphous mixture with other members of the 

 pyroxene group. From the amounts of lime and magnesia present 

 it is evident that diopside presumably makes up the greater part of 

 the molecules that accompany the sodic jadeite. 



• This analysis is of the specimen from which Penfield isolated two small crystals, on which he meas- 

 ured the crystallographic angles, and of which Merwin has determined the optical characters, some of 

 which are given on a later page. 



