25 
different varieties of the Labrador feldspar, the saloon. 
naker feldspar, or adularia, and the common feld- 5^x7 hist. 
Spar .—Among the specimens of Labrador feld¬ 
spar, more properly called opalescent feldspar, 
being remarkable for the beautiful play of colours 
which it exhibits, are several from the transition 
syenite of Laurwig in Norway.—The adularia 
(which stands in the same relation to common 
feldspar, as rock crystal to common quartz), is 
principally found on Mount St. Gothard, but not 
in the valley of Adula, from which its name is 
improperly derivedthis variety, when cut en 
cabochon, (such as the stone set in a ring) is 
commonly called moon-stone; modifications of 
crystals of this variety.— Common feldspar, vari¬ 
ously crystallized and massive, among the latter of 
which may be particularized the fine green variety 
from Siberia, called Amazon stone ; feldspar with 
imbedded fragments of quartz (graphic stone) 
from Siberia, See.—To these are added a few speci¬ 
mens of disintegrated feldspar, which passes into 
porcelain earth.—The chiastolite or made, placed 
in this table, is referred by Werner to feldspar, 
under the name of hollow spar.-—As intermediate 
between the contents of this and those of the next 
case may be considered the leucite (amphigene of 
Haiiy), of which this case contains several crys¬ 
tals belonging to the trapezoidal modification, in 
their fresh and altered state, both loose and im¬ 
bedded in lava. 
(Case 13.) Is principally appropriated to the 
e substances 
