MANUAL OF THE NILAGIRI DISTRICT. 91 



tion of that mineral. Captain Oucliterlony mentions having found a CHAP. V. 



speck of copper pyrites in a loose block derived from one of these „ 



qnartz veins, but no trace of that mineral has been found by the MmERAuta" 



surveyors after careful and repeated examination of the vein stones. 



It is possible the iron pyrites or mundic above described mav have Z'^^^T'^ i 

 , . I ^ t ■, *' haematite liow 



been mistaken tor the more valuable cupriferous mineral." found. 



With regard to the decomposition of the rocks already adverted —No copper- 

 to, Mr. Blandford observes that without a careful chemical analysis ^^^^^^' 

 of the various descriptions of gneiss present on the hills, it is of rocks! ^"° 

 difficult to account for " the unequal and irregular decomposition 

 which obtains in many cases in rocks of apparently identical 

 mineral composition. -"^ Generally it seems that the rocks contain- 

 ing little or no felspar are little liable to decomposition; the same 

 is also the case with rocks destitute of hornblende, though con- 

 taining much felspar. The existence of hardgueiss bands, e.g., at 

 Mukarte, is due to the fact that some portions of the rock contain 

 more quartz than others. 



The laterite which exists in the hills, where no regular laterite Laterite. 

 beds are found, appears to be result of the decomposition of horn- 

 blendic gneiss. ''Theiron^' observes Mr. Blandford, ''originally 

 contained in the hornblende becomes thoroughly peroxidized and 

 hydrated, and by a species of crystallization forms a mammillated 

 coating of impure limonite (brown hematite) exactly resembling 

 the characteristic surface of laterite." A good instance of this 

 occurs near the Paikare River on the road to Mukarte. 



This mineral is found in several places on the hills. It may be Kaolin ; 

 seen on the Lake road at Ootacamand, near Fairlawns, and on the ^j^^g®°"* 

 road between Paikare and Neduwattam. It is stated to contain 

 too much iron to be of much economic value. The hill kaolin is 

 formed by felspathic gneiss decomposed m situ. Ordinarily it is 

 formed from decomposed granite. Several kinds of ferruginous 

 clays occur, of varying tints, some of which might possibly be used 

 as pigments. Twenty-eight different varieties of clay were shown 

 at the Agricultural Exhibition at Ootacamand in October 1869. 

 Twenty cups manufactured from them at the Madras School of 

 Arts were also shown, also a flower vase made of the pure white 

 kaolin. The quality is stated to have been very fine. 



The physical aspect of the Nllagiris has, as already pointed out, Evideuces of 

 been greatly affected by the action of the rainfall, the erosion of °iariue action. 

 ' the rocks being in proportion to the severity of the rainfall. It is 

 : in the Kundas, for this reason, that we meet with steeper and more 

 precipitous hills and deeper and more gorge-like valleys than in 

 other portions of the range which are not open to the full burst 

 of the south-west monsoon. It is, therefore, on the portions of the 

 hills where this fresh-water influence has prevailed least, that we 



