Vol. 58.] THE WOLLASTONITE-SCAPOLITE GNEISSES OF CEYLON. 685 
says that ‘the forms present are too rough to measure except with 
the hand-goniometer; they are probably 
m(110), 6(010), (130), c(001), 0(111), n(021), 7 (201), ?d (241) ;’ 
the combinations mbzcony, mbconyd, mbcon being noted. ‘Sections 
|| 6 give an extinction of about 5° and positive bisectrix central.’ 
Plagioclase is not very common in separate individuals, and when 
present is usually referable to oligoclase (in one case labradorite). 
The felspars, in appearance and behaviour, much resemble those of 
the Charnockite Series in general. 
Augite,—pale sea-green in sections, dark bottle-green macro- 
scopically, probably always belonging to the hedenbergite group.’ 
Cleavage well developed. Extinction-angles over 40°. Occasionally 
replaced by amphibole, chlorite, calcite, etce., but usually fresh.. Rare 
in segregation-veins, where individuals do not exceed a few inches 
in diameter. On one individual (moulded by calcite) from a small 
pegmatite-patch, Mr. Richard Graham determined the forms m(110), 
a (100), b (010), o (221), and w (111). 
Quartz,—irregular elongated individuals in the acid rocks, the 
elongation parallel to the foliation. Large idiomorphic individuals 
in the segregation-veins. Often opalescent in the coarse quartzo- 
felspathic rocks. No quartz-veins occur. 
Sphene,—usually present, but never idiomorphic except where 
moulded by wollastonite in local pegmatitic patches. 
Graphite,—generally present in small flakes, as an original 
mineral. Rare in more acid types, and not noted in segregation- 
veins. One very thin vein of graphite was observed following a 
line of very slight disturbance. 
Iron-ores,—pyrite most usual; magnetite, more or less titani- 
ferous, also occurs. . 
Zircon and apatite rarely observed. 
A pophy1llite,—small idiomorphic individuals in a drusy cavity 
in a segregation-vein. The forms a(100), ¢(001), p(111) have 
been identified by Mr. Graham. 
The order of crystallization of some of the minerals is not very 
clear. Sphene, graphite, zircon, apatite, and iron-ores are the 
earliest ; wollastonite is usually the last mineral to crystallize. 
When augite, felspars, quartz, and scapolite are present together, 
the structure is generally granular. 
ITV. Oruer Locarities 1n Cry1on. 
Rocks perhaps ailied to those of Galle were brought up from the 
shaft of a graphite-mine at Nilhene (Baddegama district). Speci- 
mens composed of augite, scapolite, orthoclase, quartz, wollastonite, 
graphite, sphene, iron-ores, and calcite in various proportions were 
1 See chemical analysis, Quart. Journ. Geol. Soc. vol. lvi (1900) p. 604. 
