Palachk.] 



L lierz olite-Se rpen tine. 



'77 



quite abundant in this type of rock. Chlorite and limonite occur 

 in very small amount as decomposition products. The former fills 

 interstices among the other constituents as a scaly aggregate, 

 bright green in color, slightly pleochroic, and with faint interfer- 

 ence colors. The limonite is mostly disseminated as a pigment but 

 is concentrated in places so as to form opaque yellowish patches. 



A chemical analysis was made of the first type or hornblendic 

 facies of the intrusive rock, and the silica was determined in the 

 pyroxenic facies. The results are presented in the accompanying 

 table, together with two other analyses for comparison : — 





I. 



II. III. 



IV. 



Si O a 



47.41 



46.38 5I-58 



47-38 



Al, 3 



16.03 



14.99 



16.77 



Fe. 2 3 



2.66 



2.04 



4.64 



Fe 



7.05 



8.36 



6-73 



Mn 



trace 



trace 





Ca O 



12-33 



8.59 



10.81 



Mg 



5.81 



6.51 



4.1 1 



K,0 





•3' 



■93 



Na 2 



}*47* 



3.0S 



3.02 



P*O s 



trace 



•24 



.42 



Ti O, 



1.29 



1.05 



3-07 



H . 2 O 



2.19 



3.01 



1-25 





99.24 



99.76 



99-°3 



Sp. gr. 



2.96 



3.008 





I. Hornblendic Facies, Epidiorite, Potrero; analyst, C. Palache. 



II. Py 



roxenic Facies, 



Hypersthene Diabase, Potrero; 



analyst, 



C. Palache. 



III. Diorite-Diabase,f Mt. Diablo; analyst, Dr. Melville. 



IV. Epidiorite,;!; Eisenbuhl bei Beila. 



The silica content of the pyroxenic facies shown in analysis II 



* Calculated as Na, O. 



fH. W. Turner, Bull. Geol. Soc. Amer., Vol. 2, p. 3S7, andW. H. Melville, 

 ibid., Vol. 2, p. 412. 



jGumbel, Geognostiche Beschreibung des Fichtelgebirges, Gotha, 1S79. 



