II. 



On the Diamond Mines of Southern India, 



By H. W. VOYSEY, Esq. 



HAVING lately visited some of the principal Diamond Mines of South- 

 ern India, the few facts I have been able to collect respecting the geolo- 

 gical 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 soil, and a late writer infers from some circumstances at- 

 tending 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 vegetable matter, which gradually ac- 

 " quires a crystalline form, by the influence of time, and the slow action of 

 "corpuscular forces." 



This reasoning may apply with justice to the particular specimens 

 which have fallen under the observations of Dr. Brewster, 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 al- 

 luvial soil. 



* See Quarterly Journal of Science and Art, Oct. 1820. 



