24 
saloon, mens of compact feldspar, among which are the 
Nat7~Hist. red variety from Sweden, frequently mistaken 
for hornstone; the weiss^stein of Werner, &c. 
—Near to this is placed the feldspath com- 
facte tenace of Haiiy, which is the same as 
the jade of Saussure, called by some saussurite. 
(Case 12.) In this glass case are deposited the 
different varieties of the .Labrador-feldspar, the 
naker-feldspar, or aduJaria, and the common feld- 
spar. — Among the specimens of Labrador feld- 
spar, more properly called opalescent feldspar, 
being remarkable for the beautiful play of co- 
lours which it exhibits, are several from Norway. 
— The adularia, which stands in the same re- 
lation to common feldspar as rock crystal to com- 
mon quartz, is principally found on Mount St. Go- 
thard, but not in the valley of Adula, from which 
its name is improperly derived: the varieties, 
when cut en cabochon, (such as the stone set in a 
ring) are commonly called moonstones ; modifi- 
cations of crystals of this variety. — Common feld- 
spar, variously 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, &c — To these are 
added a few specimens of disintegrated feldspar, 
which passes into porcelain earth. — The chias- 
tolite 
