120 
LONG 
GALLERY. 
Nat. Hist. 
Case 21. Common quartz: —among the specimens 
of this widely diffused substance, which offers such 
great variety in its external aspect, the more remark¬ 
able are the hacked, corroded, and cellular quartz from 
Schemnitz, as also the pseudomorphous or supposi¬ 
titious 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 
from Brazil;— iron-flint. In this Case are also de¬ 
posited several varieties of stalagmitic quartz or 
quartz-sinter, the most remarkable among which are the 
siliceous concretions 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 fiorite), and from the island 
of Ischia. With these are placed specimens of the cerau - 
nian 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 sup* 
posed origin, they are called lightning tubes, from 
which name those of fulgurite, ceraunian sinter , astra - 
phyalite , are derived), at Drigg on the coast of Cum¬ 
berland, and latterly, 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.— Haytorite. 
Case 22 contains some more of the varieties of com¬ 
mon 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 occu¬ 
pied by the siliceous substance called hornstone , di¬ 
vided into the conchoidal and splintery varieties; 
among these are the remarkable pseudomorphous crys¬ 
tals 
