134 FOYE. 



The position in the Norm classification is : — 



Class II Dosalane, 



Order 5 Germanare, 



Rang 3 Andase, 



Subrang 4 Andose. 



A hornblende andesite from Sepulchre Mountain, Yellowstone 

 National Park, closely resembles the Kandavu variety. (Washington, 

 1903, p. 275). 



3) Hornblendc-biotite Andesite. The specimen was collected from 

 a series of flows, forming low, late-mature hills near the sea-coast, at 

 Vathilea. 



The fresh rock is of a bluish slate color, somewhat vesicular, and 

 porphyritic. Phenocrysts of feldspar and hornblende, 5 to 6 mm. 

 long and 1 to 2 mm. wide, with an occasional olive-tinted biotite, are 

 set in a purplish, light gray matrix. 



The phenocrysts of feldspar are most abundant and form 30 to 

 40 per cent of the rock. They are not zoned and have the composi- 

 tion of a basic andesine, or acid labradorite, (Ab52An48)- 



The hornblende phenocrysts are pleochroic; colorless / X, yellow 

 //Y, and olive yellow // Z. The reaction rims of magnetite, descril)ed 

 in the other hornblende andesites, are lacking here. Augite also is 

 absent. 



The ground-mass has a pilotaxitic texture and consists almost 

 entirely of feldspar. 



4) Olivine Andesite. The central segment of Kandavu, east of the 

 hornblende andesite area, which extends to the valley east of Namata, 

 is composed of olivine andesite. Specimens of this type of rock were 

 collected at Matasu and Kama. The specimen from Matasu will be 

 described. It was taken from a residual boulder on a low, lateritized 

 hill, 50 to ()0 feet high, near the sea-coast. 



The fresh andesite is a dark, slate-colored rock, hypocrystalline, 

 porphyritic, and massive. Rounded phenocrysts of feldspar, 3 to 

 4 mm. in diameter, and phenocrysts of olivine and augite are scattered 

 through a glassy matrix. 



The larger feldspars are more acid and have the composition of an 

 acid andesine, AbyoAnso, whereas the smaller feldspars, probably a 

 second generation, represent acid labradorite, Ab55An45. There are 

 zonal inclusions of glass in the larger phenocrysts. 



The augite phenocrysts are repeatedly twinned on the front pina- 



