Account of some new Vesuvian Minerals 2614 
and that it differs from all silicates of these bases, in having 
a larger proportion of alumine, and less of silex. The for- 
mula presenting its composition, is A°S+-KS. This will be 
verified by chemical examination. 
Distinguishing characters. The structure, aspect of the 
pa and chemical composition, distinguish Cavolinite 
m Davina, Nepheline, and pinite, with which it has the 
serine form in common 
The primitive form, its power of forming jelly with acids, 
and its chemical composition, distinguish it from scapolite, 
wernerite, spodumene, and prehnite. 
It is distinguished. from the mesotype of Haiiy, which has 
a vitreous fracture ; by having its fracture fibrous-lamellar, 
or silky, and by its containing potash, which the mesotype 
does not. 
itis known from apophylite, by its forming jelly with 
acids, and melting only before ae blowpipe ;_ whereas that 
mineral dissolves in acids an ore. the blewpipe Bailes. 
The Cavolinite has a regular fecal for its primitive 
form, the other, a right rectangular prism. Fimally, the 
chemical composition of the two differs entirely. 
ee are. 
Ss echt characters. 
Geometrical characters. The primitive form is an sige 
rectangular prism, in which the inelination of base P (fig. 
202) to the face M is 94°, and to the opposite, 86°. The 
natural cleavages parallel to M very distinct; those par- 
allel to P, not visi 
Physical ie SAI Hl Sp. gr. 2.77. It is scratched by 
quartz. The crystals have an fee lustre, but are mostly 
dull on the superficies, or incrusted with a yellowish fbrown 
varnish of pumice. The transverse fracture is vitreous, tend- 
ing to conchoidal: the longitudinal is lamellar. The frag- 
ments are laminar, sea oa ar and irregular. The lamine 
possess double refract 
Chemical Pidiecten.. The Acicular fragments Le for 
0 minutes in the flame of the blowpipe, do not melt. 
‘The point most exposed becomes opaline, but sraiyes its 
ordinary aspect on cooling. With phosphorus, it yields a 
button of brownish glass, which becomes opaline when cool. 
With soda it fuses inet ys producing an opaque globule 
ofenamel. With bor it affords a brown, globular, opaque 
button, translucent at ‘os ges. With nitrate of cobalt the 
mass becomes brown, mee to blueish: but the edges ex- : 
