Blasdalk. 



Contribution to Mineralogy. 



343 



result of which is reported in the same table. The only note- 

 worthy features of the two analyses are the presence of the alkali 



TABLE No. VI. 



Analyses of Diopside, Serpentine, and Albite. 



Si 2 



Al 2 O s 



Fe. 2 3 



Fe O 



MgO .., 



Ca O 



Na 2 O 



K 2 O 



H 2 O at ioo° 



H 2 O above 100 



Ti 2 



MnO 



I 



2 



3 



4 



5 



51-91 



3-55 

 1.30 

 2.65 

 16.15 

 22.85 

 •56 



51-77 

 2. 10 



49.62 

 2.97 

 2.49 

 2.99 

 19.72 

 19.14 

 .60 



33 66 

 1-36 

 •34 

 4.80 

 38.70 

 .48 

 .98 



67.09 

 20.47 



2.96 

 18.46 

 22.10 



.58 

 ■63 



.24 

 10.96 



.21 

 .86 

 .10 

 ■33 





.24 



19.70 



.27 

 •59 



1.08 



2.71 



.31 



trace 





100.47 



99-99 



100 24 



100 26 



99.62 



1. Diopside (diallage) from San Pablo, California. 



2. Diallage from Scotland, Heddle. Trans. Royal Society, Edinburgh, 



vol. 28, p. 464. 



3. Diopside (altered) from San Pablo, California. 



4. Serpentinized anthophyllite from San Pablo, California. 



5. Albite from San Pablo, California. 



metals, and of combined water. The specific gravity of the rock 

 is 3.183. The latter fact, together with the large amount of com- 

 bined water, probably indicates the beginning of the process of 

 alteration to serpentine. 



ALTERED DIALLAGE. 



A rather coarse-grained mottled rock, found in relatively large 

 masses in situ, especially from locality B. It is easily broken into 

 irregular fragments which present plane or curved surfaces, either 

 light yellowish-green or blue-black in color. Thin sections of the 

 rock show areas of a light greenish-yellow, striated mineral and 

 especially at the angles between these areas veins or masses of a 

 black opaque mineral. Magnification of the light-colored areas 

 shows that this mineral is closely related to the diallage previously 



