APPENDIX. (517 



ceding, is lively; what indeed renders this specimen still 

 more pleasing, the globules, being tinged with an extremely 

 light bat evident shade of black, have acquired by the mix- 

 ture a bluish appearance, highly grateful to the eye. 



No. 5. Finally, one of the most remarkable varieties of the 

 orbicular granite discovered by M. Mathieu, and at the same 

 time the most clearly distinct as a variety, is that which, on 

 nearly a black and equal ground, resulting from a uniform 

 mixture of white felspar and black hornblende in particles, is 

 distinguished by its globules having in general the first circle 

 white. As black is the dominant colour in this singular 

 variety of orbicular granite, the white circles which succeed, 

 and are alternated with black, participate of this tint, and 

 are, as it were, veiled with black : they are, however, very 

 distinct, owing to their contrasting with the other circles, 

 which are of the deepest black. This variety, which takes a 

 polish equally beautiful with the other specimens, and is 

 equally hard, is found in tolerably large masses. It is ad- 

 mirably adapted for urns, and other vases of a grave aspect. 



Such are the principal varieties of the orbicular granite, 

 for the discovery of which we are indebted to M. Mathieu. 

 I have thought right to give these details at length, the bet- 

 ter to delineate a rock of which nature has been so little pro- 

 digal. I reserve all the facts, that I may resume them when, 

 if I am able, I may occupy myself with the theory of this 

 stone 3 for if it be clearly demonstrated, as every thing seems 

 to show, that this is the native site from which the block of 

 Taravo was torn, an exact datum will be afforded of a very 

 singular geological fact. 



GLOBULAR PORPHYRY OF CORSICA $ 



Its disposition in large veins. 

 It was reserved for M. Mathieu to find on its natal spot. 



