98 MENACHANITE IN MICACEOUS SCHIST. 



Thus I can no longer doubt, that menachanite, or the fer- 

 riferous oxide of titanium, enters into the composition of 

 this micaceous schist, and occasions its black colour; and 

 that it is these metallic grains, which, in consequence of 

 the decomposition of the rock, are washed down by the wa- 

 ters, and thrown upon the shore after separation by wash- 

 ing. 



This sand From these observations we find, that the granular and 



therefore a » 



component sandy form, under which menachanite appears, is by no 



part of a un means occasioned, as has hitherto been supposed, by the 



roitive rock. ,. , ,. . „, /.' J . A 



action ot the water washing it along. We nave seen, that 



the menachanite, as soon as it is separated from its gangue, 

 appears in the same granular and sandy form as on the shore 

 of Sestri. The situatiou of this mineral therefore must be 

 considered as one of the most ancient among metallic sub- 

 stances, since it is found among the component parts of a 

 primitive rock ; and appears not to have been in its original 

 Analogous to s t ate even when this rock was formed. Some analogy may 

 be perceived between these sandy grains of menachanite, and 

 the gold dust, that was erroneously supposed to be separated 

 from ores of this metal, and mixed with sand by the waters. 

 But this gold dust has already been found in soil brought 

 from some other place, which leaves us uncertain as to the 

 Other in- period, when the gold was reduced to this form. I see no- 



stances of sand th' m g to connect this singular situation of the metachanite 

 t^rocics!" l wU 1 an y geological epoch but the sandy depositions, and 

 thin strata of sand, which the illustrious de Saussure has 

 found iuterposed and almost mingled with the composition 

 of primitive mountains. Menachanite, as well as these 

 sands, may have been reduced to granular fragments in some 

 jnore remote ages of our globe. 



Whatever may be thought of these conjectures, the situa- 

 tion of menachanite in the shining schist of the mountains 

 of Pegli is established. Thus, since the torch of the natural 

 sciences has begun to illumine the land of Liguria, the vi- 

 cinity of Genoa has already made known the natural situa- 

 Variol.tein t'°» of two minerals, the variolite in mount Raraazzo*, and 

 mount Ra- ^ ne rjienacharjite, which forms the subject of this paper, 

 znazzo. 



* Annates du Museum. 



IV. 



