Vol. 56.] CEYLON ROCKS AND GRAPHITE. 599 



present. The hornblende is partly derived from the pyroxene. This 

 rock is a hornblende-gabbro. (See PL XXXIII, fig. 6.) 



(6) Quartz-Norite. 



A beautiful example of quartz-norite occurs not very far from 

 Kurunegala, on the right-hand side of the Ragedara road, forming 

 a rock known as Muttatugala, which has been quarried for road- 

 metal. The rock is coarse-grained, and greenish-grey to brown. 

 The hypersthene, plagioclase, and quartz are easily recognizable 

 macroscopically ; the only other minerals are magnetite and a grain 

 or two of hornblende. The plagioclase (27° 29°, probably labra- 

 dorite) has a blue sheen. The hypersthene occurs in large patches 

 which may exceed 2 inches in diameter, or it may be more 

 regularly distributed : the peripheral portions of the large patches 

 may often be seen to enclose the felspar in an ophitic manner. 

 Crystalline form is quite absent. In very thin sections the 

 hypersthene is scarcely pleochroic, but in thicker cleavage-fragments 

 a normal pleochroism is strongly marked. My friend, Mr. S. 

 Hastings, has kindly analysed this pyroxene in duplicate, with the 

 following results : — 



I. II. 



Per cent. Per cent. 



Si0. 2 50-97 49-93 



ALO, 1-30 -15 



FeO 27-21 2961 



MgO , 20-87 21-22 



100-35 100-91 



Specific gravity = 3'55 



The ferrous oxide was weighed as ferric oxide and calculated into ferrous ; 

 the alumina is probably overestimated in the first analysis. 



(7) Serpentine. 



A dark-green decayed rock, found on the spoil-heap at Nilhene 

 graphite-mine, is formed chiefly of serpentinous material. Much 

 of this is derived from enstatite, the characteristic cleavage and 

 straight extinction being occasionally distinguishable in less decayed 

 nuclei. Other portions appear to have been derived from olivine. 

 A few crystals of colourless augite and sphene also are present. 

 It is noteworthy that, out of numerous specimens collected at Nilhene, 

 this alone appears to be of the nature of a massive rock and not 

 of a vein-product. 



(8) Limestones. 



White crystalline limestones occur in several localities, such as 

 Hakgala, Talatuoya near "Kandy, and between Matale and Dam- 

 bulla, on the Anuradhapura road. The stairways at Sigiri are 

 made of white limestone, often containing pale mica and prisms of 

 blue apatite. At Anuradhapura it has been used in some cases for 



