NATURAL HISTORY. 
53 
GALLERY.] 
or morion, cairngorm, citrine, &c. ; specimens of rock crystal enclosing 
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 Demono¬ 
logy), &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 quartz ;—-flexible 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 w hich were 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 derived), at Drigg 
on the coast of Cumberland, and lastly, by the iate Capt. Ciapperton, 
(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 substance, being purely siliceous, 
but presenting the form of datolite. 
Case 22 contains some more of the varieties of common quartz : 
prase , w T hich appears to be an intimate mixture of that 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 wnod converted into hornstone, being the wood- 
stone of Werner ; hornstone balls from Haunstadt in Bavaria_Of flint, 
a w T ell 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.; the botryoidal, 
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 
