1836.] 



Neelgherries and Koondalis* 



quartz (which is the only other mineral entering in the composition of 

 the pegmatite, besides felspar) are still visible in the same situation, as 

 when the rock had not undergone decomposition, having become more 

 brittle, and easy of disintegration. 



The porcelain earth is not to be confounded with that which results 

 from the decomposition of the pure felspar veins, so frequently seen in 

 the sienitic granite. By simply looking at both specimens, the differ- 

 ence is discovered (No. 12). The latter has no sandy particles in its 

 composition, such as are found in the other, which by such addition is 

 better adapted for the manufacture of pottery,, in. which silicious sand is 

 a necessary ingredient. 



1 speak with some hesitation regarding a mineral I found only in 

 one place on the Neelgherries, and I am doubtful whether it exists in 

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

 ly resembling umber, particularly that kind which is exported from the 

 Island of Cyprus (No. 13). 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 pro- 

 bability, 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 undecomposed 

 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. 14). 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 Kaitee 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. 15). 



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

 rich in metal, are, one near the village of Vartsigiri (Kotagherry), 

 and the other close to, and traversing, the Lake of Ootacamund in two 

 places. The specimen from Vartsigiri (No 16) 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 just below the building called 



