356 



University of California. 



[Vol. i. 



suppose. The pleochroism is quite pronounced in shades of brown- 

 ish red and yellow. In sections normal to the acute bisectrix the 

 mineral proves to be optically positive. 



The apatite has the same characters as those given for the 

 mineral in the nepheline-pyroxene-malignite. The crystals are, 

 however, smaller and less abundant than in that type of rock. 

 The hematite is represented only by an occasional scale in some of 

 the slides. It is of a deep red color, translucent on the margins, 

 but opaque in the thicker central portions. A few grains of mag- 

 netite may be found by careful search, usually inclosed in the 

 aegerine-augite. A canary yellow pleochroic mineral is found in 

 some of the slides, but, on account of small dimension of the grains, 

 could not be satisfactorily determined. It has a strong double 

 refraction, but lower refractive index than epidote, and the extinc- 

 tion angle measured against the direction of elongation has a high 

 value. 



Chemical Analysis. — For the following analysis of this interest- 

 ing rock, the writer is indebted to Mr. W. C. Blasdale, instructor in 

 chemistry in the University of California. 



Analysis of Garnet- Pyroxene- Malignite. 



Si0 2 



51.88 



Al,0 :t 



I4-I3 



Fe 2 :i 



6.45 



FeO 



•94 



CaO 



10.81 



MgO 



344 



Na 2 



6.72 



K,0 



4-57 



TiCX 



•33 



PA 



.96 



HX> 



.18 



Total 



100.41 



Sp. g. 



2.88 



From the above data it will be apparent that this malignite 

 approaches in its mineralogical and chemical characters the basic 



