part 1] AND ASSOCIATED HOCKS OF MOZAMBIQUE. 97 



Plate IX. 



Fig. 1. Biotite -gneiss (49), 3 miles from Ibrahimo, on the road to Mosuril. 

 Chief minerals : quartz, orthoclase, microcline, oligoclase, biotite, 

 and muscovite. X 20. (See p. 54.) 



2. Hornblende-gneiss U89), Ampwihi Crossing. Chief minerals: horn- 



blende, andesine-labradorite, perthitic orthoclase, and biotite. X 20. 

 (See p. 58.) 



3. Garnetiferous amphibolite (194), Ampwihi Crossing. Chief minerals : 



hornblende, labradorite, garnet, and titaniferous magnetite. X 20. 

 (See p. 58.) 



4. Garnetiferous biotite -gneiss (97), Norray Hills. Chief minerals : 



quartz, microcline, andesine, biotite, and garnet. X 20. (See p. 62.) 



5. Eclogite (77), Norray Hills. Chief minerals : garnet, amphibole, 



pyroxene, and rutile. X 20. (See p. G2.) 



6. Quartz-garnet-pyroxene rock (78), Norray Hills. Chief minerals : 



garnet, pyroxene, scapolite (meionite), and quartz. X 20. (See 

 p. 62.) 



Plate X. 



Fig. 1. Augite -granite (27), Sawa Cave, Bibawe Mountains. Chief minerals : 

 quartz, orthoclase, microcline, oligoclase, and pyroxene. X 20. 

 (See p. 73.) 

 2.' Norite rich in sphene (37), floor of the Namieta Biver, south of Peone 

 Hill. Chief minerals : labradorite, augite, enstatite, and sphene. 

 X 20. (See p. 75.) 



3. Butile- apatite vein in augite -adamellite (21). Chief minerals : apatite, 



rutile, sphene, and pyrite. X 20. (See p. 73.) 



4. Butile-muscovite rock (74), near Monapo Biver, east of Mount Tibwe. 



Chief minerals : muscovite, rutile, and quartz. X 20. (See pp. 73- 

 74.) 



5. Pyroxenite (33), half a mile from the foot of Ericola, in a gully 



draining into the Nrassi Biver. Chief minerals : diopside, horn- 

 blende, and enstatite. X 20. (See p. 81.) 



6. Monazite-grains (residue No. 5), separated from the sand of the 



Bwibwi Biver above the confluence with the Potela Mazi. X 20. 

 (See p. 83.) 



Plate XL 



Map of the Bibawe Mountains and the Nrassi Basin, on the scale of 

 5 miles to the inch, or 1 : 316,800. 



Discussion. 



Dr. J. W. Evans spoke of the thorough way in which the Author 

 had worked out his materials and the interest of the conclusions at 

 which he had arrived. The Author had proved his point ahout the 

 local absorption of the limestone in the granitic magma, hut this 

 could not be said with regard to the suggestion that the biotite- 

 gneiss resulted from the absorption of an argillaceous rock by a 

 magma representing a simple binary granite containing only quartz 

 and felspar. An argillaceous rock would not afford the magnesia 

 required, nor did such magmas usually form extensive intrusions. 

 The discussion in the paper on the mode of production of the 

 inselberg landscape was of especial interest. 



Q. J. G. S. No. 293. h 



