308 Dr. Du Riche Preller—Orystalline Rocks, N. Piémont. 
DISTRIBUTION OF PIETRE VERDI IN THE LANZO VALLEYS. 
Ringe I, from Rocciamelone to Lanzo, on right of Usseglio Valley ; 
36 km. 
Serpentine: Gran Uja (2,686 m.); Civrari (2,302 m.). 
Peridotite, lherzolite, and serpentine: Arpone (1,600 m.); Roe 
Neir (1,516 m.). 
Rives II, from Croce Rossa to Lanzo, between Usseglio and Balme 
Valleys; 30 km. 
Amphibolites, prasinites, and euphodites: ‘Yorre d’Ovarda 
(3,075 m.); M. Ciaron (1,863 m.). 
Serpentine: Becca Nona (2,765 m.); Morosa (2,135 m.); 
Calcante (1,644 m.). 
Rivek III, from Ciamarella to Lanzo, between Balme and Grande 
Valleys; 30 km. 
Serpentine: Uja Mondrone (2,964 m.); Rosso (1,774 m.). 
Amphibolites, prasinites, and euphodites: Doubia (2,464 m.); 
Plu (2;201 m:): 
Rinee IV, from Levanna to Lanzo, on left of Val Grande; 36 km. 
Amphibolites, prasinites, and euphodites: Bellavarda (2,345 m.). 
On the whole, serpentines predominate in the first, amphibolites, 
prasinites, and euphodites in the second ridge, while in the third the 
two series are about equal, and in the fourth they are only repre- 
sented by the Bellavarda complex wedged between the gneiss 
formation on the left and the mica-schists on the right. ‘The two 
series of the calc-schist horizon share their aggregate area of about 
240 square kilometres in fairly equal proportions ; that of the eastern 
or mica-schist horizon, occupying 120 square kilometres, is about 
equally divided between the nucleus of peridotite and lherzolite, and 
the surrounding belt of serpentine with associated euphodite. 
The pietre verdi of the Lanzo valleys appear in all their varieties 
and at all levels from 500 m. altitude at Lanzo, which town 1s built 
on serpentine, up to 3,500 metres on the highest points of the central 
and enclosing ridges. At the lower levels, more especially in the 
central part of the synclinal trough, they alternate conformably with 
calc-schist. and crystalline limestone intercalations, having shared in 
the acute folding and contortions of the latter; while at the higher 
levels they form enormous banks, cliffs, and bastions like separate 
massifs, such as the serpentine complexes of Gran Uja, Civrari, Becca 
di Nona, and Uja di Mondrone, and, again, the amphibolic, prasinitic, 
and euphoditic groups of Torre d’Ovarda, Ciaron, Doubia, and 
Bellavarda mentioned in the table. 
The chloritic prasinite known as ovardite and mentioned in the 
preceding papers takes its name from the Torre d’Ovarda group in 
the Balme Valley, which latter is, moreover, famed for its splendid 
specimens of garnet, epidote, and other crystals. All the pietre verdi 
of more or less secondary composition and their schists present their 
usual actinolitic, glaucophanic, zoisitic, chloritic, and talcose varieties, 
and are often garnetiferous and eclogitic. ‘They all exhibit the usual 
marked tendency to chloritic decomposition, i.e. to pseudo-serpentine 
or serpentinous schist, a phenomenon which applies equally to the 
