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XXXVTIT. Extract from a Memoir by M, Mathieo^ ofi 

 the Discovery of several Blocks of orbicular Granite re" 

 cent ly found in Corsica *, 



J. HE insulated block of orbicular granite which was found 

 in Corsica in 1785, on the small plain of Talavo, half a 

 league from the sea, on the shores of the Gulf of Valin- 

 co, on the Istria road, not far from a place called la Stan- 

 2ona, and which Messrs. Sionville and Barral \vcre the first 

 to describe, fixed the attention of mineralogists, from the 

 singular form assumed in this rock by the white semi- 

 transparent feldspar and the amphibole or horne blende of a 

 deep black, a little greenish, arranged in several concentric 

 circles, which had given rise to species of round or oval 

 bowls, immersed in a confused mixture of the same two 

 mineral substances which form the basis of the rock. 



This stone, so singtilar by the system of its formation, 

 and by the effect which it produced when polished, made 

 it very much sought-after for cabinets, and it soon became 

 rare and of high price. 



In vain did Messrs. Barral, Sionville, and after them Do- 

 lomieu, Besson, and several other mineralogists, make in- 

 quiries after the rock which had given birth to the insu- 

 lated and partly smooth block, which some convulsion had 

 transported and buried in the small plain of Talavo 5 — all 

 iheir pains were useless. 



Notwithstanding their want of success, a Corsicanna- 

 tnralist, M. Ram passe, was more fortunate ; because his 

 knowledge of the language and manners of the inhabitants 

 of the mountains admitted of his pursuing, with a hammer 

 in his hand, the chain of mountains from which he pre- 

 sumed that the block of the orbicular rock of Talavo must 

 have been torn at a very remote period by the action of the 

 sea. 



M. Rampasse has executed this arduous journey, during 

 which he collected a fine series of rocks and other mine- 

 rals ; but he was not more fortunate than the rest with re- 

 spect to the globular granite. His inquiry, however, made 

 us acquainted with the position of a porphyritic rock 

 crowded with globular bodies, in general larger than those 

 of the stone found at Talavo ; and the formation of which, 

 without being absolutely the same with the latter, never- 

 theless resembled it considerably j but the rock, of a differ-r 



* Annalti du Mutium d'HisloiTt NaturelUf tome xkv. p. 82, 



cut 



