422 Geological Sketch of the Neilgherries. [Aug. 



any quantity in those hills. It is a brown ferruginous clay, very 

 closely resembling amber, particularly that kind which is exported 

 from the Island of Cyprus (No. 17). I found it between two large 

 blocks of decomposing sienitic granite, or rather hornblende rock, 

 with garnets, close to the bund of the lake. 



The next rocks to be described are two metallic ores, in all 

 probability, originally imbedded, as veins, in the rock : which last 

 being now decomposed, they are left imbedded in the lithomargic 

 earth : indeed, one of these ores is still seen as a vein, in the unde- 

 composed rock. 



The first is the magnetic iron ore, so common in many parts 

 of India, and which, besides the metal, contains variable proportions 

 of quartz (No. 18). The places where I have met with this iron 

 ore are marked in the map : in some of them the ore is imbedded in, 

 the lithomargic earth, while in others it is like a vein in the rock. 

 I saw it in this last position in the road descending to Kaiti valley, 

 where the metal is very little in quantity, compared with the granular 

 quartz, which in some parts of the vein predominates to the almost 

 entire exclusion of the metal (No. 19). 



The two places on the Neilgherries, where I have seen this ore 

 very rich in metal, are, one near the village of Vartsigiri (Vrota- 

 gherry), and the other close to, and traversing, the Lake of Oota- 

 camund in two places. The specimen from Vartsigiri (No. 20) 

 is very compact and rich in metal. I took it from a large block, probably 

 the outgoings of a thick bed at the southern extremity of the valley, 

 at the other end of which the village stands. 



Generally speaking, the quartz is lamellar, very rarely granular, 

 and it seems to alternate with the metal in parallel laminae. The 

 appearance, composition, and proportion of the ingredients of this 

 magnetic iron ore are very different in different places ; nay, in the 

 same vein. For instance, the vein seen iust below the building 

 called Gradation Hall, between the road, and the margin of the lake, 

 in its N. E. extremity, has a compact, metallic structure, highly 

 magnetic, with hardly any quartz (No. 21) : a few yards to the south- 

 west, the vein contains a good deal of quartz ; the metal is more 

 oxidated, although maintaining still its magnetic powers (No. 22). 

 Following the vein in the same direction, we see it appear in the 

 opposite side of the lake, in the banks of the road, which goes round 

 and close to the lake. There the ore has lost a good deal of its 

 quartz ; the iron is more oxidated, and the rock assumes a kind of 

 columnar structure (No. 23). This is the appearance of the vein in 

 the section for the road. But the out-croppings of the vein at the 



