427 
Geology. 
by the discovery of Mr. Gregor, who found menachine 
to be a constituent part of basalt. 
We shall now mention particularly the age of the dif- 
ferent species of the Menachine genus. 
a. Rutile is found in Hungary, Switzerland, and Rus- 
sia. The Hungarian varieties are usually imbedded in 
mica-slate ; the Russian are generally accompanied with 
or included in rock-crystal, and those found at St. Go- 
thard are accompanied with rock-crystal, felspar, and 
other fossils. 
b. Octahedrite , another species of menachine, occurs in 
very old veins that traverse gneiss and mica- slate. These 
veins are composed of felspar, axinite, iron-mica, rock- 
crystal, chlorite, and sometimes mica. It has been hither- 
to found only in Dauphiny. 
c . Rutilite . — The late Dr. Mitchell, in his excellent 
Memoir on Menachine, in the last volume of the Irish 
Transactions, has the following account of the geognos- 
tic situation of rutilite: “ In the mountains of Passau, 
this fossil is found imbedded in a coarse granular aggre- 
gate of felspar and hornblende, and felspar and actynoiite ; 
therefore belonging to the genus Greenstone, and order 
of Primitive Trap. In Norway, it occurs in rocks be- 
longing to the same formation in which the celebrated beds 
of magnetic ironstone lie, and is associated with horn- 
blende, and several other individuals of a tribe not as yet 
sufficiently examined and described, but which evidently 
constitute middle links between actynoiite and hornblende, 
and to which the names Acanticone and Arendalite have 
been applied. Near Dresden and Brun, it is found dis- 
persed through sienite, and at Galway, in Ireland, in an 
uncommonly beautiful porphyritic sienite. Hence it ap- 
pears that this fossil has only occurred in rocks belong- 
ing to primitive trap, or in sienite, the last crystallization 
Vol. III. ^ 3’G 
