NATURAL HISTORY. 
173 
GALLERY.] 
crystal enclosing various substances, such as rutile, brown 
iron-stone, micaceous iron, acicular antimony, actinote, 
asbest, chlorite, &c.; groups of rock crystal; some speci¬ 
mens 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 great variety 
in its external aspect, the more remarkable are the hacked, 
corroded, and cellular quartz from Schemnitz, as also the 
pseudcmorphous 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 deposited by the celebrated hot spring in Ice¬ 
land, the Geyser; another variety of it is the pearl - 
sinter from Santa-Fiora in Tuscany (whence it has ob¬ 
tained the name of fiorite ), and from the island of Ischia. 
With these are placed specimens of the ceraunian sinter 
or those enigmatical 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 suiter , astraphyaliie , are derived), at Drigg on 
the coast of Cumberland, and lastly, by the late Capt. 
Ciapperton, 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 stalag¬ 
mitic quartz and calcedony.— Haytorite , a substance purely 
sileceous, 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 av anturino-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 
