Ill 
lodged in the quartzy mass.—Part of this case is occu¬ 
pied by the siliceous substance called hornstone , di¬ 
vided into the conchoidal and splintery varieties; 
among these are the remarkable pseudomorphous crys¬ 
tals from Schneeberg in Saxony, derived from various 
modifications of calcareous spar ; also beautiful speci¬ 
mens of wood converted into hornstone, being the 
wood-stone of Werner; hornstone balls from Ilausi- 
stadt in Bavaria.—Of flint , a well known substance, 
some interesting varieties are deposited. The remain¬ 
der of this and the whole of the following case are oc¬ 
cupied by calcedonic substances. Among the speci¬ 
mens of common calcedony the most remarkable are, 
the smalt-blue variety from Felsobanyain Transylvania, 
crystallized in obtuse rhombohedrons; the branched and 
stalactical calcedony from Iceland, &c.; the botryoidal, 
from Ferroe; nodules, including water (enhydrites) 
from Monte Berico, near Vicenza, where they occur in 
volcanic rocks. 
Case 23. Calcedonic substances continued: cut 
and polished pieces of calcedony with red and black 
dendritic and other figures, called mocha stones; va¬ 
rieties with white, brown, and black, straight or curved 
lines, some of which were probably among the sub¬ 
stances of which the costly vasa murrliina of the an¬ 
cients were made; red and yellowish varieties of cal¬ 
cedony called cornelian. — Plasma. — Heliotrope , an in¬ 
timate mixture of calcedony and green earth, which, 
when containing disseminated particles of red jasper, 
is commonly termed blood-stone.—The beautiful and 
much esteemed variety of calcedony called chrysoprase , 
hitherto only found at Kosemiitz in Silesia, and which 
owes its colour to oxide of nickel, as does the green 
siliceous earthy substance, named pimelite , which ac¬ 
companies it. To these are added specimens of some 
varieties of the siliceous compounds called agates , in 
which common calcedony, carnelian, or heliotrope ge¬ 
nerally form a predominant ingredient. 
Case 24. One half of this case is occupied by the 
different 
LONG 
GALLERY. 
Nat. Hist. 
