141 
—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 pirn elite, which 
accompanies it. To these are added specimens 
of some varieties of the siliceous compounds 
called agates , in which common calcedony, 
carnelian, or heliotrope generally form the pre¬ 
dominant ingredient. 
Case 23. One half of this case is occupied 
by the different varieties of jasper, such as they 
are enumerated by Werner, viz. the globular or 
Egyptian jasper , found chiefly at Cairo in 
rounded pieces, which appear not to owe their 
form to rolling, but to be original, and pro¬ 
duced by infiltration;—the ribbon jasper or 
striped jasper, the finest varieties of which are 
found in Siberia ;—the variously-tinted common 
jasper ;—the agate jasper, found only in agate- 
veins, and the porcelain jasper , produced by 
the action of subterraneous fire on clay slate. 
The other half of this case contains opaline sub¬ 
stances, viz., specimens of the noble opal , which 
owes its beautiful play of colours to a multiplicity 
of imperceptible fissures in its interior;—the sun 
or jire opal ;—the common opal, a translucent 
white variety of which, appearing yellow or red 
when held between the eye and the light, is 
called girasol j—the semi-opal , agreeing in its 
principal 
LONG 
GALLERY. 
