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themselves vary much in purity and in dolomitic character ; the 

 minerals most frequently occurring and indeed nearly always 

 present are forsterite and phlogopite ; graphite is frequently 

 abundant in small flakes ; other accessory minerals include 

 pyrite, blue apatite, spinel, amphibole, chondrodite, seapolite, &c. 

 Of inclusions in the limestones there are (a) aggregates of the 

 characteristic accessory minerals ; (b) inclusions of rocks indis- 

 tinguishable from the pyroxene granulites except for the usual 

 presence of seapolite and sphene. 



Certain rocks composed essentially of pyroxene with seapolite, 

 amphibole, mica, calcite, and sphene occur sparingly in bands 

 interbedded with the other rocks ; separating limestone from 

 granulite ; or as inclusions in the limestones. 



The (lialle Ciroup. — A group of rocks allied to these but distin- 

 guished by the presence of woUastonite is found at Galle. These 

 rocks include types composed of pyroxene, seapolite, sphene, 

 woUastonite, and graphite, and all transitions from these to rocks 

 composed of quartz and felspars. There are also remarkably 

 coarse dykes composed essentially of orthoclase, quartz, ami 

 woUastonite, crossing the foliation ; the individuals of wolias- 

 lonite, moulding the idiomorphic crystals of quartz and ortho- 

 clase, are sometimes as much as 3 feet in length. 



The name Ba]ail<>'0(la jiTOup is given to a series of granitic rocks, 

 intrusive in the Oharnockite Series or granulites ; tiie granites 

 occur in dykes and lenticular masses, the best exposures so far 

 known being in the Balangoda district. The principal types 

 include zircon granite, allanite-granite or pegmatite, magnetite 

 granite, and granite without accessory minerals. But although 

 not yet discovered in situ (except thorianite, which occurred very 

 sparingly in a pegmatite vein at Gampola, and ilmenite, which is 

 common in several types), the following additional minerals are 

 almost certainly derived from rocks of the Balangoda group : 

 baddeleyite, beryl, cassiterite, chrysoberyl, fergusonite, geikielite, 

 ilmenite, rutile, some spinels, thorianite, thorite, topaz, and some 

 tourmaline. 



Rocks which are alteration products of those already mentioned 

 include bands of chert (opaline chalcedonic rock), which usually 

 occurs replacing the carbonates of the crystalline limestones, 

 minerals such as spinel and graphite remaining in the chert 

 unaltered. Laterite (cabook) is a typical decomposition product 

 of the granulites, and is of interest on account of its use as a build- 

 ing material, and on account of its chemical composition, consist" 

 ing largely of aluminium hydrate. Various Clavs, including 

 kaolin (china clay, " kirimeti,'" *' makul ") are derived from the 



