Account of some new Vesuvian Minerals. 25% 
Varieties. 1. Primitive— 
q (see fig. 194 bis.) regular hexa- 
: edral prism, | 
8 height is ri eee than 
t @the breadth. nu 
Ps "Pen dndecw: 
Peas 6 . th 
same shortened—(fig. 197.) 
imensions. "The usual size 
of these prisms is 8 millimetres 
in length, by 4 in width; they 
do oceur 15 by 10—and the 
largest even 30 by 20. Colour 
s brown. It is found transpa- 
wie translacent and opaque : 
and with pearly or opaline lus- 
re. 
Locality. -It oceurs in a 
analogous to that in which 
the Umboldilite and zurlite are 
found. pers however, very 
rarely with Davina 
The Is ‘tis sally accompa- 
nying Davina, are Wollastonite, 
Garnets, calcareous spar, pu- 
mice, black spinelle and mica. 
Distinguishing Characters. It approaches nearly to 
Nepheline, by its crystalline form, by its action under heat, 
and with acids, but has characters so marked as to distinguish 
it at first sight. 
Comparison of the characters of the two minerals. 
Nephelr eline. 
Primitive form, regular, 
Ole 
ecular, 
desta ok hexahedral, the height of the 
avi 
ve form 
tiossnedirch the height of the 
prism greater than the width. 
are very a 
The orions of of the seconda- 
ry form are less long than 
broad. 
VOL. XI.—NO. 2. 
long. 
33 
scarcely apparent, and on 
seen by aid ‘of a strong light. 
The prisms of the second- 
ary form are less 
