'166 M. Brongniaut on the position 



Ramazzio, and probably on the coast from Genoa to Inurea^ 

 &c. 



b. Diallage rock (Euphotide of Haiiy, Granitone of the 

 Italians, Gabbro of M. von Buch). A rock composed, in 

 the cantons to which I confine my observations, of compact 

 or sublamellar felspar, of greenish serpentine, of schiller 

 spar (diallage metalloide), and sometimes perhaps of quartz. 



On the western shore from Genoa to Savona ; the felspar 

 is granular, with quartz and more talc than diallage. 



At Voraggio ; the felspar is granular, with diallage or talc 

 of a dull green colour. 



At Figline, on the north of Florence ; compact waxy 

 felspar accompanied by lamellar blueish grey felspar, with 

 diallage and a little green serpentine. 



In the valley of Suvero and Cravignola, to the north of 

 Brugnato, &c. 



3. The Jasper formation (terrain jaspique) composed of 

 extensive beds or mountains of jasper, subdivided into strata 

 or even extremely multiplied and parallel laminae, some- 

 times red with a dull fracture and coarse paste (at Prato ; 

 at Pietramala), sometimes red, of a finer paste, with either 

 violet or dull green zones. It resembles the ribbon jasper 

 of Siberia, though it does not possess either its hardness, its 

 beautiful colours, or its fine grain, and it differs still more 

 from it by perfect infusibility (at Montenero near Ro- 

 chetta).* 



There are two jaspers. The greed and translucent part, 

 which possesses a little of the exterior characters of petro- 

 silex, is infusible with the blowpipe ; the red part is equally 

 so, but it becomes discoloured, and the surface of the scales 

 becomes slightly shining. 



This formation contains, as a subordinate rock, beds of 

 altered red jasper, passing into red whetstone schist, and, 

 as casual minerals, black oxide of manganese, compact and 



* Dr. MacCulloch has given an account and synopsis of jasper rock, 

 in his geological classification of rocks, division, 'Occasional rocks;' he 

 states,"that it occurs indiscriminately both in the primary and secondary 

 classes." (p. 539). (Trans.) 



