nt affirms that the lavas of Etna consist of labradorite,
pyroxene (augite), peridot (olivine), and titaniferous iron. Rose was
the first to prove that the lavas of Etna do not contain ordinary
felspar (or potash felspar), but labradorite (or lime felspar.)
(_Annales des Mines_, 3 serie, t. viii., p. 3.) Elie de Beaumont
detached a quantity of white crystals from the interior of a lava found
between Giarre and Aci Reale; these were analysed by M. Auguste Laurent
with the following results in 100 parts:--

Silica 47.9
Alumina 34.0
Oxide of Iron 2.4
Soda (Na{2}O) 5.1
Potash (K{2}O) .9
Lime 9.5
Magnesia .2
-----
100.0

Von Waltershausen gives the following as the composition of two
specimens of Labradorite from Etna:--

I. II.

Silica 53.56 55.83
Alumina 25.82 25.31
Sesquioxide of Iron 3.41 3.64
Magnesia .52 .74
Lime 11.69 10.49
Soda 4.09 3.52
Potash .54 .83
Water .95 --
------ ------
100.58 100.36

Specimens of Augite from Etna have been examined by Von Waltershausen
and Rammelsberg, with the following results:--

_Greenish_ _From_ _From_
_Black._ _Black._ _Mascali._ _Monti Rossi._

Silica 47.63 51.70 49.69 47.38
Alumina 6.74 4.38 5.22 5.52
Protoxide of Iron 11.39 4.24 10.75 7.89
" Manganese .21 -- -- .10
Magnesia 12.90 21.11 14.74 15.29
Lime 20.87 18.02 18.44 19.10
Sesquioxide of Iron -- -- -- 3.85
Water .28 .49 .51 .43
------ ----- ----- -----
100.02 99.94 99.35 99.56

Olivine is generally met with in the lavas of Etna. It has an olive, or
bottle-glass green colour, and is d