Vol. 58.] WOLLASTONITE-SCAPOLITE GNEISSES OF CEYLON. 683 
Weathering.—The felspars are generally very slightly cloudy, 
and not quite so fresh as in most of the inland charnockites. The 
scapolite exhibits often a fibrous structure due to incipient decom- 
position. The rocks generally speaking are, however, very fresh. 
In some specimens the wollastonite has been replaced by a minute 
quartz-calcite mosaic. 
Relation to the Charnockite Series.—It will be seen from 
the map that the rocks of the Galle Group occupy a belt or zone 
with normal members of the Charnockite Series on each side. 
No actual junctions are exposed, and probably no sharp contact 
could be recognized, even if complete exposures were to be 
seen. Probably there is rather a gradual transition ; bands of acid 
rocks in the Galle Group are quite like acid members of the Char- 
nockite Series, showing’ the close connection between the two groups 
of rocks. 
ITI, Nores on tHE MINERALS. 
W ollastonite,—never idiomorphic, but moulding other minerals; 
by no means always present; occasionally replaced by a quariz- 
calcite mosaic. Very large individuals in segregation-veins. It is 
interesting to note that Prof. Lacroix emphasizes the original 
character of the wollastonite in his Ceylon rocks, which, though 
probably not from Galle, are of very similar type. 
Scapolite (wernerite),—constantly with small rod-and-lath- 
like inclusions parallel to the vertical axis. When decomposed has 
a cloudy look and fibrous structure. More frequently present 
than wollastonite. Never in large individuals, and not found in 
segregation-veins. Like the wollastonite, evidently an original 
mineral; often accompanying quite fresh felspars. 
A graphic intergrowth of scapolite and orthoclase-microperthite 
(fig. 2, p. 684) occurred at the junction of a small quartz-felspar- 
pyroxene vein with a green-and-white wollastonite-scapolite - 
pyroxene rock. It is interesting to compare this intergrowth 
with the intergrowths of scapolite and diopside, and scapolite and 
orthoclase, which were found in a variety of rock included in the 
crystalline limestone of the Hakgala district.’ 
Felspars,—usually orthoclase, with very minute microperthitic 
structure ; often showing a peripheral zone of intergrowth with very 
fine vermicular quartz. Perhaps microcline-microperthite is some- 
times present. The microperthitic structure is usually very fine; in 
other cases, the plagioclase-inclusions are larger and distinctly 
twinned. Large and small idiomorphic orthoclase-individuals, 
without inclusions, occur in the segregation-veins. Some from a 
drusy cavity were kindly examined by Mr. Richard Graham, who 
1 A. K. Coomdraswaémy, ‘Crystalline Limestones of Ceylon’ Quart. Journ. 
Geol. Soe. vol. lviii (1902) p. 409. 
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