174 NATURAL HISTORY. [NORTH 
mass.—Part of this Case is occupied by the siliceous sub¬ 
stance called horn stone , divided into the conchoidal and 
splintery varieties; among these are the remarkable pseu- 
domorphous crystals from Schneeberg in Saxony, derived 
from various modifications of calcareous spar ; also beauti¬ 
ful specimens of wood converted into hornstone, being the 
wood-stone of Werner; hornstone balls from Haunstadt in 
Bavaria.—Of jlmt, a "well known mineral substance, some 
interesting varieties are deposited. The remainder of 
this and the whole of the following Case are occupied by 
calcedonic substances. Among the specimens of common 
calcedony the most remarkable are, the smalt-blue variety 
from Felsobanya in 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; varieties with 
white, brown, and black, straight or curved lines, some 
of which were probably among the substances of which 
the costly vasa murrhina of the ancients were made; 
red and yellowish varieties of calcedony called carnelian 
— Plasma .— Heliotrope, an intimate mixture of calce¬ 
dony and green earth, which, when containing disse¬ 
minated 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 sub¬ 
stance, named pimelite , which accompanies it. To these 
are added specimens of some varieties of the siliceous com¬ 
pounds called agates , in which either common calcedony, 
carnelian, or heliotrope generally form a predominant in¬ 
gredient. 
Case 24. One half of this Case is occupied by the dif¬ 
ferent varieties of jasper, such as they are enumerated by 
Werner, viz. the globular or Egyptian jasper, found chiefly 
near Cairo in rounded pieces, which appear not to owe their 
form to rolling, but to be original, and produced by infil- 
