1836.} the Country between Hyderabad and Nagpur* 199 



iron contained in the sienife ; but this takes place at the surface, and 

 seldom acquires any great degree of hardness. Specimens of the 

 granite in the neighbourhood of Hyderabad are numbered 14 ; and 

 the appearance of the surface of that polished by the continual passage 

 of hyenas, in the entrance of the caverns formed in the pile of gneiss 

 or granite of the " Chita hill," near the cantonment, has been 

 described in the 1st volume of the Journal of the Asiatic Society. 

 The greenstone occasionally has distinct crystals of felspar scat- 

 tered through it, without the porphyry thus formed, losing the re- 

 markable degree of toughness possessed by the black rock ; but, as 

 observed by Sir H. Davy, the decomposition of the felspar is more 

 rapid than of the other parts. The greenstone is familiarly known 

 by the name of " black granite," and forms, when finely polish- 

 ed, the beautiful tombstones of the Golconda mausoleums, and the 

 pillars of that in which Hyder andTippu Sultan are deposited, at 

 Serin gap'atam. The remarkable quartz veins in the neighbourhood of 

 Hyderabad have been described by Voysey and Christie ; it is there- 

 fore only necessary to mention, that they occasionally exhibit a more 

 or less regular crystallization, and at the same time, acquire the fine 

 tints of the amethyst. It is seldom that they are sufficiently regular 

 and perfect for the purposes of the lapidary ; such specimens were, 

 however, discovered a few years ago, close to the European barracks, 

 and at a little distance from a great greenstone dyke, but not in direct 

 contact with the quartz bed containing the crystals, which, on the 

 contrary, passes into the ordinary sienitic granite of the country. The 

 colour of the amethystine quartz seems to be derived from magnetic 

 iron ore, which is disseminated in grains both through the milky quartz 

 and the granite, amongst which they are found, and has not been notic- 

 ed elsewhere in the neighbourhood. The amethystine quartz was again 

 met with 60 miles north of Secunderabad, near Bekanurpettah, in loose 

 masses, along with that variety of laterite found near Beder, and 

 described by Voysey, and which is seen along the coasts of Malabar 

 and atBoranghur in the Southern Concan resting on basalt. The rising 

 ground on which they were found is composed of granite ; but the 

 country around is of a black trap soil, and numerous low flat ranges 

 of basaltic hills are seen to the north, the east, and the west. A vein 

 of white quartz is also met with as at Secunderabad, but the specimens 

 differ, in containing irregular shaped geodes of agate, lined with crys- 

 tals, or a red opake mamillary quartz, approaching to calcedony. The 

 iron in these is usually imperfectly mixed with the quartz, and from 

 the appearances above described, and the quartz having in several 

 specimens been changed into a red jasper, the surrounding trap may 

 be supposed to have altered the rocks. The colouring matter seems 

 to have been afforded by the laterite, which is found in the neighbour- 



