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of the Appennines. 
the same rocks. They appear, in some points, in the Abruzzo 
and in Monte Circeo, and in Calabria, occupying considerable 
tracts of country, every where resting on primitive rocks. The 
rock named Macigno and Pietra serena in the vicinity of Flo- 
rence, of which the coarse varieties are employed as a building 
stone, and the finer worked into columns, and various architec- 
tural ornaments, agrees in its essential characters with greywacke. 
But this rock oecurs not only around Florence and in the neigh- 
bouring country of Sienna, but every where in Italy, where tran- 
sition rocks make their appearance. Our author met with it at 
the northern foot of the Bocchetta , also near to Carrara and Mas - 
sa , and in the Appennines of Lucca. It rises to the height of 
6546 feet above the level of the sea, in the Cimone in the Ap- 
pennines of Modena. The greywacke of Italy does not vary so 
much in its grain as that of Germany ; but, like the German, it 
occurs sometimes in thick beds, sometimes with a slaty structure, 
and the latter with vegetable impressions. 
In the Appennines, as in other countries, clay-slate is the con- 
stant attendant of greywacke, with which it frequently alternates. 
It occurs most frequently in the form of common clay-slate , with 
different colours ; sometimes as roofing-slate , particularly above 
Lavagna , between Genoa and the Gulph of Spezia, where it is 
quarried to a great extent, and is exported far and wide under 
the name Pietra di Lavagna. 
Flinty slate , with brown, black, and green colours, occurs in 
different places in beds in the transition-rocks. Hausmann met 
with it in hills between Massa and Lucca. 
Talc-slate occurs more frequently, and in larger masses. Its 
occurrence along with transition-rocks has hitherto been little 
attended to, although it appears in the Alps in rocks of the same 
description. It passes imperceptibly on the one side into clay- 
slate, and on the other into chlorite-slate. Our author found it 
in these slates in the hills of the Bocchetta , and above Pietra 
Santa , where it dips under the brecciated marble of Seravezza. 
Saussure met with it on the coast between Genoa and Andora. 
The talc and chlorite are frequently intermixed with quartz, 
and this compound forms a kind of oven-stone (gestellstein), 
which sometimes passes into true mica-slate. Saussure and 
Faujas St Fond discovered this latter rock between Genoa and 
