784 H. S. WASHINGTON DECCAN SALTS AND PLATEAU BASALTS 



Attention should, however, be called to the figures for chromium, and 

 especially vanadium, shown in Harwood's complete and excellent analyses. 

 In this they resemble the Faroe basalt analyzed by him and, as we shall 

 see, many other basalts of this region. Hauser's analysis (number 7) is 

 so unsatisfactory as not to merit discussion, except to point out that in 

 its general features it much resembles the first five. 



The norms of these basalts (except number 6) are given in Table VI. 



Table VI 



Norms of Iceland Basalts 



1 2 3 4 5 A 



Quartz 3.60 5.88 



Orthoclase 3.89 1.11 1.67 1.67 7.23 3.34 



Albite 20.44 15.72 17.82 16.77 32.49 20.96 



Anorthite 20.02 30.30 22.80 33.36 15.57 24.19 



Diopside 20.66 21.88 30.34 21.58 9.34 20.93 



Hypersthene 17.38 10.83 10.87 10.89 17.66 IS. 92 



Olivine 13.50 6.48 9.20 2.11 



Magnetite 3.71 1.39 7.19 2.55 3.02 3.4S 



Ilmenite 7.90 4.56 2.89 4.26 4.41 4.71 



Apatite 1.01 0.34 0.34 2.69 1.01 



1. Holmatindur. III. "5. 3(4) .4(5). 



2. Grunda-fjord. III. 5. 4. "5. 



3. Reykjavik. III". 5. "4. "5. 



4. Allamannagja. III. 5. 4. "5. 



5. Hecla. (II) III : (4)5. "3. 4. 

 A. Average. III. 5. "4. 4 (5). 



These norms show much the same features that we have observed be- 

 fore. Several of the basalts show excess silica, while others show consid- 

 erable olivine, but none contain the nephelite molecule. It is noteworthy 

 that only the earliest and the latest basalts are quaric, and it is to be 

 seen that the normative feldspar of these two contains a much greater 

 proportion of albite to anorthite than do the others. In Wright's Hecla 

 specimen the feldspar is about Ab 4 An 3 , in those from Holmatindur, 

 Reykjavik, and in the average it is about Ab 1 An 2 , while in the Grunda- 

 fjord and Allamannagja rocks it is about AbjAn^. It is also noteworthy 

 that in most of these norms the amounts of diopside and of hypersthene 

 or of hypersthene and olivine are approximately equal, as is evident from 

 the norm of the average rock; but at Reykjavik the amount of diopside 

 is about double that of the non-calcic femic silicates, while the reverse is 

 true of the Hecla specimen. The general relations of these femic mole- 

 cules are corroborative of Holmes' determination of the pyroxene as an 



