﻿MK. J. A. HOWE rETEOLOGICAL NOTES [Aug. I905, 



No. 39, south of Yankerckhovenville (felspathic ehlorite-horn- 

 blende-schist). — A pale greenish-grey rock, with dark spots, of a 

 compact fine-grained texture. 



The bulk of the rock is composed of a granular aggregate of 

 felspar, with a subordinate amount of granular quartz. The 

 dark spots noticed in the hand-specimens are crushed and distorted 

 green hornblende-crystals. Minute flakes of chlorite are 

 abundant throughout the rock, and exhibit a regular orientation. 

 Very small granules of e pi dote are common. 



Hocks from Dungu and the Makassa Rapids. 



Prom the Makassa Rapids on the Uelle, midway between Dungu 

 and the mouth of the Obu River, three specimens were obtained. 

 Two of these, Nos. 18 & 19, may be called phyllites, the other rock, 

 No. 20, is a gneiss. 



Wo. 18, Makassa Rapids (phyllite). — A compact greenish rock, 

 with marked undulose schistosity, and shiny surfaces when freshly 

 broken. The slide exhibits fine granular quartz, with abundant 

 streaks of talc and mica. Much granular calcite is present. 

 Throughout the rock small plates of chlorite are regularly 

 scattered. Groups and individual minute needles of r utile are 

 common. 



No. 19, Makassa Rapids (phyllite). — This rock is similar in 

 appearance and composition to No. 18. A number of dark iron- 

 stained crystals are seen in the thin section ; they probably repre- 

 sent decomposed pyrites. 



These two rocks may possibly represent altered calcareous shales. 

 Similar rocks were noticed at Dungu. 



No. 20, Makassa Rapids (granulitic microcline-gneiss). — A pale, 

 fine-grained, foliated rock. 



The bulk of the rock is composed of a granular aggregate of 

 quartz and clear felspar. Ill-defined masses of micaceous 

 feltwork with epidote-granules are abundant; epidote and 

 sphene occur in small grains. Included in the granular matrix 

 there are broken crystals of microcline and plagioclase, and 

 larger grains of quartz; strain-twinning and undulose extinction 

 are common. 



Rocks from between Vankerckhovenville and Farach. 



No. 14, between Yankerckhovenville and the River Ewado 

 (diabase). — A fairly coarse- grained rock, with a reddish tinge. 



Large hypidiomorphic prisms of plagioclase, mostly near 

 labradorite, are somewhat clouded ; pericline and albite-twinning 

 occur together frequently. Moulded upon the felspar in an ophitic 



