1822.] Dr. Davys Travels in Ceylon. 65* a 



granite is still rarer. The only good example of it with which tq 

 am acquainted is at Trincomeilee, where it occm's of a beautiful-^ 

 quahty, ork the sea shore, about half a mile beyond Chapel Point, 

 imbedded in a granitic rock. The quartz, in this instance, is 

 black or grey rock crystal, and the felspar highly crystalline, and 

 of a bright flesh colour. The quartz envelopes the felspar in very 

 thin hexagonal or triagonal cases, so that nothing can be more 

 different in appearance than the longitudinal and transverse 

 fracture of the rock. Neither is sienite common. It occurs, 

 rather forming a part of rocks of a different kind, than in great 

 mountain masses. Well formed gneiss is more abundant than 

 granite. Its peculiar structure may be seen in many places, but 

 no where more beautiful than at Amanapoora, in the Kandyan 

 provinces, where it consists of white felspar and quartz in a 

 finely crystalline state, with layers of black mica, containing 

 disseminated through it numerous crystals of a light coloured 

 garnet. The more limited varieties of primitive rock, as quartz, 

 hornblende, and dolomite rock, seldom occur in the form of 

 mountain masses. 



Quartz in large veins and imbedded masses is abundant in the 

 granitic rocks. It is in general milk-white, translucent, full of 

 rents, and so very friable as to remind one of unannealed glass. 



Pure hornblende and primitive greenstone are far from uncom- 

 mon. They constitute no entire mountain or hill that I am 

 aware of, but they form a part of many, particularly of Adam's 

 Peak, and of the hills and mountains adjoining Kandy. 



The varieties of dolomite are almost as numerous as those of 

 granite. When purest, it is snow-white, generally crystalline, 

 often highly crystalline, composed of rhombs that are easily 

 separated by a smart blow, but rarely finely granular. I found 

 a specimen of the highly crystaUine kind, of specific gravity 

 1*93, composed of 



Carbonate of magnesia . , 56*0 



Carbonate of lime 36*9 



Alumina 4-1 



Silica '. 1-0 



Water 2-0 



100-0 



A very fine granular kind, of a beautiful whiteness, well 

 adapted for statuary purposes, is found in the neighbourhood of 

 Fort Macdonald. A specimen of it that I tried was of specific 

 gravity 2*74, and contained only a very small proportion of car- 

 bonate of magnesia. The varieties of most importance are mix- 

 tures of dolomite with felspar and mica, and even quartz. It is 

 in rocks of this kind that the nitre caves of the interior are found* 



In external character and general structure, the varieties oC 

 New Series, v o l . 1 1 1 . f 



