54 
NATURAL HISTORY, 
[north 
In this Case are also deposited several varieties of stalagmitic quartz 
. or quartz sinter , the most remarkable among which are the siliceous con¬ 
cretions deposited by the celebrated hot spring in Iceland, the Geyser; 
another variety of it is the pearl-sinter from Santa-Fiora in Tuscany 
(whence it has obtained the name of Jiorite), and from the island of 
Ischia. With these are placed specimens of the ceraunian sinter or 
those enigmatical siliceous tubes which w r ere discovered in the sands of 
the Senner Heath in the County of Lippe (where, on account of their 
probable origin, they are called blitz-rohren, or lightning tubes, from 
which name those of fulgurite , ceraunian sinter , astraphyalite , are de¬ 
rived), at Drigg on the coast of Cumberland, and lastly, by the late 
Capt. Clapperton, (see Append, to his Journal,) near Dibbla in the 
Tuarick country, Africa, from which localities specimens are here 
deposited. The hyalite is placed here as a mineral related equally to 
stalagmitic quartz and opal;—the haytorite , a pseudomorphous sub¬ 
stance, being purely siliceous, but presenting the form of datolite ;— 
the avanturino quartz. 
Case 22 contains some more of the varieties of common quartz: 
prase , wdiich appears to be an intimate mixture of that substance and 
actinote;—as also some varieties of the cat's eye (mostly from Cey¬ 
lon), in which the chatoyant lustre is generally produced by nearly 
invisible fibres of amianth lodged in the quartzy mass.—Part of this 
Case is occupied by the siliceous substance called hornstone , divided 
into the conchoidal and splintery varieties; among these are the re¬ 
markable pseudomorphous crystals from Schneeberg in Saxony, derived 
from various modifications of calcareous spar ; also beautiful specimens 
of wood converted into hornstone, being the wood-stone of Werner; 
hornstone balls from Haunstadt in Bavaria—Of flint , a well known 
mineral substance, some interesting varieties are deposited; flint con¬ 
taining water, &c. 
The remainder of the contents of this and the whole of those of the 
following Case relate to 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, enclosing water (enhydrites), from Monte Berico, 
near Vicenza, w 7 here 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 w 7 hich 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 calcedony and green earth, which, when con¬ 
taining 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 accompanies it. To these are added 
specimens of some varieties of the siliceous compounds called agates, 
in which common calcedony, carnelian, and heliotrope generally form 
the predominant ingredients. 
Case 24. One half of this Case is occupied by the different 
