The Geology and Physiography of the Lawnswood Area. 
57 
east of the upper inetasediments. This is petrologically indentical with 
unlateritised specimens (22530) from the l)ase of the upper metasediments 
and is correlated with horizon 11 (Table 1.). 
(ii) The Biotite-cordierite-quartz-sericitc-sillimanite schist (19190) is 
frequently darker in colour and more gneissic than group (i). The biotite 
occurs in markedly elongated, strongly iileochroic ])lates — Y and Z = 
brown, X =: very light brown to colourless, absoriition X ■" Y — Z, c 
X ~ 0°, (-)2y very small. Pleochroio haloes around zircon grains are 
frequent. The quartz is very elongated and contains gas-lupiid inclusions 
and minute inclusions of sericile, rutile, rounded zircon and rare sillimanite. 
Cordierite was observed in an irregular intergrowth with quartz in one slide 
(19953) but equidimensional sericite aggregates are possibly pinite pseudo- 
moiqjhic after cordierite. The sericite aggregates are evidently derived 
some from bands of sillimanite and some from an equidimensional mineral 
— probably cordierite or even felspar (see text fig. 4). The sillimanite is 
Text Pig. 4. 
Biotite-corderite-quartz-aericite-sillimauite schist (19190), show- 
ing a band of sericite pseudomorphic after sillimanite (small prisms 
with high reUef) and equidimensional grains consisting of sericite 
after corderite (or felspar). Four rounded grains of rutile are seen in 
this Held. 
