APPENDIX. 



lar granite, others are found of similar nature, more or less 

 saliant, but the number of them is not great. M. Mathieu 

 imagines them to be a species of kernels much more solid 

 than the hornblende rock which gave them birth ; and that 

 this, not being of a composition equally hard, has been unable 

 in an equal degree to resist the action of the weather, and 

 consequently, becoming gradually decomposed in part, has 

 left the orbicular granite bare. 



The space occupied by these singular productions, at least 

 such of them as are exposed to sight, including that filled by 

 the hornblende rock, is about a hundred yards 5 after which 

 the ordinary granite reappears. 



M. Mathieu, not content with simply affording me in- 

 structive information respecting the discovery he had made, 

 was so kind and liberal as to enrich my collection with a 

 series of beautiful specimens of all the varieties of orbicular 

 granite he had collected on the mountain of Sainte Lucie. 



I here annex a short description of those which appeared 

 to me the most interesting. 



No. 1. A specimen, the thickness of which is one inch and 

 three lines, diameter four inches, of orbicular granite, re- 

 sembling as well in composition, shade of colour, and hard- 

 ness, as in the form of its globules, that of Taravo, possessing 

 also like that some small brilliant points of a substance 

 apparently metallic, and of a silvery white colour, which 

 affects the magnet, and belongs to the class of magnetic 

 pyrites. This substance takes a beautiful polish; grains of 

 this description are not numerous, but distinctly sprinkled 

 in the mass, as well as in the globules themselves of this 

 granite. In every respect, in short, it seems a similar species 

 to that of the valley of Taravo ; but M. Mathieu informed 

 me that this beautiful variety is not frequent : it exists, how- 

 ever, in its original site, which suffices. 



No 2. Orbicular granite, the composition of which is 

 the same with that of the granite of the plain of Taravo, but 



