98 M. Voysey on the Diamond Mines' of Southern India. 



specting the geological relations of that gem, I take the liberty 

 of laying before the Asiatic Society. 



A knowledge of the matrix of the diamond has long been 

 a desideratum in mineralogy. It has been hitherto supposed 

 that this mineral was only found in alluvial soils ; and a late 

 writer infers, from some circumstances attending a particular 

 diamond, which had passed under his examination, that the 

 matrix of this precious stone was neither a rock of igneous 

 origin, nor one of aqueous deposition, " but that it probably 

 originates like amber, from the consolidation of perhaps vegeta- 

 ble matter, which gradually acquires a crystalline form, by the 

 influence of time, and the slow action of corpuscular forces.' 1 * 



The reasoning may apply with justice to the particular spe- 

 cimens which have fallen under the observation of Dr Brew- 

 ster ; but as it is fully ascertained that diamonds have, for two 

 centuries at least, been found in a rock generally supposed to 

 owe its origin to deposition from water, the application will of 

 course be limited to the case of diamonds found in alluvial 

 soils. 



A considerable range of mountains called the Nalla Malla 

 (Blue Mountains ?) lies between 77° and 80° of east longi- 

 tude. Their highest points are situated between Cummum in 

 the Cuddapah district, and Amrabad, a town in the province 

 of Hyderabad, North of the Kistna, and vary in height from 

 2000 to 3500 feet above the level of the sea. 



The outline of these mountains is flat and rounded, very 

 rarely peaked, and as they run N. E. and S. W., the ranges 

 gradually diminish in height, until, in the former direction, 

 they unite with the sandstone and clay-slate mountains of the 

 Godavery, near Palunshah. Their union is certainly not very 

 distinct, but is sufficiently so to entitle them to be considered 

 geologically as the same range. In a southern and south-west 

 direction, they probably extend considerably beyond the Pa- 

 goda of Tripati. The most southern point that has fallen 

 under my observation, is Naggery Nose, a well known sea- 

 mark on the coast of Coromandel. Travellers to Hyderabad 

 make a considerable detour for the purpose of crossing these 

 mountains in their most accessible parts. Among the western 



* Edin. Phil Journ. vol. iii. p. 100. 



