450 



DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



Augite-hiotiie Malignite. — The first specimen was collected at a ledge about 

 50 yards west of the contact with the older Kruger-mountain schists and 1,200 

 yards west of the small lake on the top of the mountain-plateau. This rock is 

 dark-coloured, medium to fairly coarse-grained, and of gabbroid habit. (See 

 Plate 39, Figure C). The essential minerals are augite, (with rare outer shells of 

 olive-green hornblende), biotite, microperthite, microcline, nephelite, and prob- 

 ably soda orthoclase. Apatite, a little titaniferous magnetite or ilmenite, and 

 titanite are original accessories. Melanite is also an abundant accessory but 

 in this case all of the garnet may have been derived from the pyroxene through 

 crush-metamorphism. A little hydronephelite and more abundant muscovite, 

 which seems to replace nephelite, are present as secondary products, but on the 

 whole the rock is to be described as fresh. 



The order of crystallization among the original minerals is : apatite ; iron 

 ore; titanite; augite; feldspars; nephelite. The order is unusual in that the 

 nephelite follows the feldspars. 



The chemical analysis of this specimen (No. 1100), by Professor Dittrich, 

 resulted as follows : — 



Analysis of malignite, Kruger alkaline hody. 



SiOL 



TiO„ 



A1 2 0, 



FeA 



FeO. 



MnO 



MgO 



CaO 



Na„0 



K 2 



H,0 at 110°C. . 

 HoO above 110 C C. 



P s O B 



CO 



Mol. 



50-49 



842 



•92 



011 



15-83 



155 



6-11 



038 



3-04 



042 



•11 



001 



3-38 



084 



7-99 



143 



3-12 



050 



6-86 



073 



•29 





1-20 





•42 



003 



■07 





Sp. gr. 



99-83 

 2-S49 



Tiie calculated norm is:- 



Orthoclase. . 



Albite 



Nephelite.. . 

 Anorthite.. . 

 Diopside.. .. 

 Wollastonite. 

 Magnetite.. , 

 T]menit9.. .. 

 Hematite.. . 



Apatite 



Water 



40-59 

 7-34 



10-22 

 8-90 



18-14 

 1-97 

 7-42 

 1-67 

 •96 

 •93 

 1-49 



99-63 



