66 C. A. SUSSMILCH. 



Petrographical Description of the Inclusions. 



The following plutonic rocks were found to occur (1) 

 hypersthene gabbro, (2) augite peridotite, (3) enstatite 

 peridotite (saxonite), (4) pyroxenite. These all occur in 

 the form of more or less rounded fragments and boulders 

 embedded in the monchiquite, the roundness being probably 

 the result of corrosion by the molten dyke rock. 



I. Hypersthene Gabbro. 



a. Megascopic Characters. 

 Colour, black and white, mottled 

 Fracture, rough 



Crystallin ity , phanerocrystalline 



Granularity I relative > even 



J ' ( absolute, medium, grainsize about 2 mm. 



Minerals visible, 1. plagioclase, 2. pyroxene. 



b. Microscopic Characters. 

 1. Orystallinity, noncrystalline 



Texture \ 2. Fabric, allotriomorphic granular 

 ( 3. Grainsize, 1*7 mm. 



Minerals present (in order of decreasing abundance) 



i. Pyroxene { £ hypersthene 



ii. Labradorite (medium variety) 

 iii. Magnetite 

 The combined pyroxenes predominate over the felspar. 

 The relative proportions of the former vary, in some slides 

 the hypersthene predominates over the augite, in others 

 the contrary is the case. The rock is remarkably fresh. 



II. Augite Peridotite. 

 a. Megascopic Characters. 

 Colour, brownish-black 

 Fracture, rough 

 Crystallinity, phanerocrystalline 



