420 A. K. Coomdraswdmy — The Balangoda Gvonp. 



Another exposure (Map, Fig. 1) is seen near the bridge over the 

 Denagama Oya, about 6 miles from Balangoda on the Haputale 

 road. Small idiomorphic zircons (-re- inch) are scattered sparingly 

 in the rock, which resembles that of Massena estate, but is of 

 somewhat coarser grain. Ilmenite is common, the zircon quite 

 scarce. Other exposures ai'e found along the line of strike on the 

 left bank of the stream. The granite seems to form a series of 

 lenticular masses. At one point the rock becomes well foliated 

 (as if by pressure), the small crystals of biotite being closely packed 

 and sweeping round the augen orthoclase. Well-formed zircona 

 1^ inch in length are to be found. 



A similar foliated zircon granite is exposed by the roadside 

 1^ miles further on, just beyond the 91st milepost ; the zircons vary 

 from iV to i inch in length, and are of the usual light-brown colour. 



No junctions were observed in the instances above referred to. 



Near Haldummulla and about 18 miles from Balangoda a small 

 granitic dyke was seen in the Weli Oya vallej' about half a mile 

 above the road, crossing foliation in the Charnockite series and 

 containing a few minute zircons just visible to the naked eye. 



In the Bamberabotuwa district a large number of small intrusive 

 pegmatites or granite dykes were examined on Hopewell estate 

 (15-16 miles from Balangoda), where they are well exposed, and 

 cross the foliation of the Charnockite series in all directions; only 

 two were found to contain minute ci'ystals of zircon sparingly dis- 

 tributed. Zircon may occur in others, but so rarely as to be 

 overlooked. This exhausts the list of localities where macroscopic 

 zircons have been seen in situ. 



Zircons of all sizes (up to 1^ inches or more) occur abundantly 

 in every stream and river gravel, and are found in quantities when 

 gemming operations are carried on, joining a large proportion of 

 the heavy residue (ndmbu^) at the bottom of the gemming-basket : 

 the clear-coloured varieties are of value as gems ; the remainder 

 is rejected. The irregular zircons described by Mr. Spencer ^ occur 

 in this way in various parts of the Balangoda and Bamberabotuwa 

 districts. Near Koudrugala zircon is very abundant in large 

 individuals. Well-developed twins on e (101) are found. With 

 the zircon are associated ' thorianite,' thorite, ilmenite. Large 

 zircons have also been found in gemmings from the Hatton district. 

 Zircon is also abundant over a wide area in the Southern Province 

 in the Galle, Matara, and Morawaka districts, and no doubt also 

 at Eakwana ; the same rocks may be expected to be met with in 

 these districts. 



Allanite granites. — Allanite granites are well exposed in two- 

 places in the Balangoda districts. It is some years since Mr. W. D. 

 Holland discovered a granite or pegmatite dyke, crossing foliation 

 in the Charnockite series, in the bed of the Wewel Dola near the 

 lower end of his estate of Dik Mukulana, and containing allanite 

 in some abundance. The determination of allanite was confiriued 



' A Sinhalese term which may with advantage be adopted. 

 - Nature, April 14th, 1904, p. 575. 



