158 Professor Hausmann on the Geognostical Structure 
granular compound of Saussurite and Diallage, which is known in 
Florence under the name Granitone , and to which the late Abbe 
Hauy gave the name Euphotide. Many places in the Appen- 
nines shew, what indeed was proved by the elder Targioni To- 
zetti, that these two rocks are but modifications of the same com- 
pound. In the vicinity of Prato and Xnpruneta, both rocks oc- 
cur so intimately combined, as to shew that the serpentine is no- 
thing else than an intimate mixture of diallage and Saussurite, 
with which asbestus is often intermixed, by which the quantity 
of magnesia of the rock is increased in quantity, and its hard- 
ness diminished. Diallage occurs crystallized, on the junction 
of the granular and compact rock, imbedded in serpentine. Gab- 
bro has hitherto been considered as a member of the primitive 
class of rocks. It may occur in other places, along with primi- 
tive rocks ; but here, in the Appennines, it appears as an un- 
doubted transition rock, of the truth of which Hausmann first 
convinced himself, on the northern and southern acclivity of the 
Bocchetta, where serpentine, and the granular compound of 
diallage and Saussurite, occur in considerable masses in transition 
clay-slate, which alternates with compact limestone, talc-slate, 
and greywacke. In the vicinity of Prato, and in many other 
places in Tuscany, Hausmann observed the greywacke slate, 
calcareous clay-slate, and limestone, dip under gabbro. Among 
the different rocks which occur along with gabbro in the Appen- 
nines, jasper and limestone deserve particular notice. The first 
occurs in the vicinity of Prato, in the form of a bed, under the 
gabbro, generally of a reddish-brown colour ; and there, as in 
other places, occasionally penetrates into the mass of gabbro. 
The limestone, particularly in the mountain of Genoa, as in the 
valley of Polzevera, occurs in alternating beds with the gabbro ; 
and often also completely intermixed with it, appears sometimes 
compact, sometimes as marble, with white, greenish and reddish 
colours, and forms mixtures with the serpentine, which resemble 
some varieties of the verde antico. Of this kind is the Polzevera 
marble, which is worked into so many forms. 
The structure of the transition formations, as here given, does 
not show any general regularity in the succession, although such 
appears to be the case in particular instances. The direction 
and dip of the strata vary very much. A general view of the 
