M, dicx. Brongniart sur les caracieres Zoologigues, Sc. 213 
lavas, such as the shining black lavas re Sepa 
white lates of feldspar, and a profusion of deep blac Bogs 
pyroxene, and those of Licatia inclfing the same 
nerals, and large greenish crystals of chrysolite rata 
-d by minute grains of the same, have nothing analogous in. 
any of = ——— rocks of Sicily—the Abbe F. suppo~ 
ses that e lavas of Sicily are derived from primitive 
rocks which ne from the mountains of Pelorus under 
tna and the extinct voleanoes; that the ancient lavas 
are formed from the prper om less 2 rasta strata of 
these rocks, and that th ‘ 
rought up from gr pieptie where” the rocks are more 
compound and stored with minerals which are not found in 
the upper strata.—The ancient lavas around the base of 
tna, such as the rocks of Molta and those of the cyclops 
are aS simple as those of the extinct volcanoes of Val di 
Noto, and were probably of the same period. 
Besides these minerals, which compose the paste of 
the lavas, there are others found in the fissures and cav-~ 
ities of the recent lavas deposited by the condensed va- 
pours. These are muriate of Ammonia, very abundant, 
collected as an article of commerce—several other muri- 
ates, A aera those of soda and iron ; carbonate of so- 
d Fer oligiste in brilliant scales, ane an the 
evitias and implanted in groups upon : 
lavas.—In the ancient lavas of Val di Noto and the base 
of tna, such as the mountains of Paterno, and the rocks 
of the c ‘clops—various minerals are found deposited in 
the cavities by infiltration, viz. carbonate of lime crystalli- 
zed, zeolite and analeime (cyclopite. Ferr.) 
ba 
, © Sur les Caracteres Zoo~ 
ee _ a ar 
Ann, le of 
A Se des Formations, uvec ‘application. de a3 ‘carac~ 
teres f /RAIE 
es @ la sctels, aie “ 6 pe = ins 
ar Alexandre Bron (Ann. des 1.) 
6. Pikorsat. 2 oe 
Tar design of this Memoir is siaectatiials shdtelative 
Value of geological and mineralogical characters in deter- 
mining the contemporaniely of formations particularly in 
reference to certain formations of chalk. The particular 
