NATURAL HISTORY. 
165 
GALLERY.] 
various substances, such as rutile, brown iron-stone, micaceous iron, 
acicular antimony, actinote, asbest, chlorite, &c.; groups of rock 
crystal; some specimens of rock crystal in a wrought state are added, 
among which is Dr. Dee’s show-stone (see Walter Scott’s Demon¬ 
ology), &c. 
Case 21. Common quartz: among the specimens of this widely 
(diffused substance, which offers such a great variety in its external 
aspect, the more remarkable are the hacked, corroded, and cellular 
quartz from Schemnitz, as also the pseudomorphous or supposititious 
crystals, principally derived from modifications of calcareous and fluor 
spars; and, with regard to colour, the blue quartz, called siderite, from 
Salzburg, and the rose or milk quartz , which are both used as ornamental 
| stones ; — fibrous quartzflexible sandstone ( itacolumite ) from Brazil 
and China -fetid quartz , from Nantes ;— iron-flint. In this Case are 
also deposited several varieties of stalagmitic quartz or quartz-sinter , 
the most remarkable among which are the siliceous concretions de¬ 
posited 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 fiorite ), and from the island of Ischia. 
With these are placed specimens of the ceraunian sinter or those enig¬ 
matical siliceous tubes which were discovered in the sands of the Senner 
Heath in the County of Lippe (where, on account of their probable 
origin, they are called lightning tubes, from which name those of 
! fulgurite , ceraunian sinter , astraphyalite , are derived), at Drigg on the 
coast of Cumberland, and lastly, by the late Capt. Clapperton, near 
Dibbla in the Tuarick country, Africa, from which localities specimens 
are here deposited. The hyalite is placed here as a mineral related 
both to stalagmitic quartz and calcedony ;—the haytorite , a pseudo¬ 
morphous substance, being purely siliceous, but presenting the form of 
datolite. 
Case 22 contains some more of the varieties of common quartz: 
prase , which appears to be an intimate mixture of this substance and 
actinote ;—the avanturino quartz ;—as also some varieties of the cat's 
eye (mostly from Ceylon), 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 remarkable 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. 
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.; thebotryoidal, 
from Ferroe; nodules, enclosing 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 
