70 NATURAL HISTORY. (Minerals.) [north 
lomonite, also called efflorescent zeolite, because most of its varieties are 
subject to decomposition by exposure to the air;— a suite of speci- 
mens of comptonite from Vesuvius, lining the cavities . of a pyroxenic 
lava, &c. , accompanied by gismondine and other crystallized substances ; 
together with thomsonite , which is supposed to be only a variety 
of comptonite ;-—gmelinite or hydrolite ; — levine, and some other scarce 
zeolitic substances. . 
Case 29. To the same family of minerals belongs the prehnite , the 
grass-green variety of which, discovered in South Africa by the Abbe 
Rochon, has been mistaken for chrysolite, chrysoprase, and even emerald ; 
—to this also belongs the koupholite of Vauquelin. The substance known 
by the name of Chinese jade or you-stone, (kyonk tshein of the Bur- 
mese,) is likewise placed with prehnite, to which it has been referred lay 
Count Bournon ; but no chemical analysis has as yet been given of it : 
(among the vessels wrought out of Chinese jade in this Case is a cup, 
the gift of the king of Ava to the late Lieut. - Col. Burney, when British 
Resident at that court, and by him presented to the British Museum. ) 
With this is placed the harmotome or cross stone, (also called 
andreolite, after Andreasberg, in the Hartz, where it was first dis- 
covered,) divided into baryte-harmotome and lime- or potassa-harmo- 
tome, to which latter are to be referred the Vesuvian minerals called 
zeagonite, gismondine , or abrazite , and the philipsite. (Of andreolite, 
a magnificent specimen is deposited, presented by King George IV.) 
The remaining space in this Case and the greater part of 
Cases 30 and 31 are occupied chiefly by feldspathic substances and 
minerals more or less nearly related to feldspar. The most remaikable 
and important species is the common feldspar , among the crystallized 
varieties of which may be particularized— the fine green variety from 
the Ural, called amazon stone ; the suites of variously modified crystals 
from Baveno in Piedmont, from Siberia, and from Silesia ; feldspar with 
embedded crystals and fragments of quartz (graphic stone, graphic 
granite), from Siberia, &c. the Labrador feldspar (also called opa- 
lescent feldspar, from its often exhibiting a beautiful play of colours 
in cut and polished specimens, of which a pretty complete suite is 
added), chiefly from the coast of Labrador and from the transition 
syenite of Laurwig in Norway * the adularia or naker feldspar, prin- 
cipally found on mount St. Gothard, but not in the valley of Adula 
from which its name is derived : the fine variety from Ceylon, when cut 
en cabochon, is called moon-stone; and a yellow naker feldspar with reddish 
dots has obtained the name of sun-stone, which is also sometimes given to 
the beautiful avanturino variety of common feldspar placed in this glass- 
case; — ice-spar and sanidine or glassy feldspar, both nearly allied to com- 
mon feldspar ; alhite or clean elandite, the finest specimens of which are 
those from Dauphine and Siberia; and pericline, united by some minera- 
logists with the preceding species, from St. Gothard, Tyrol, &c. ; — 
anorthite from Vesuvius; — oligoclase, also called natron-spodumen — 
together with some other species separated, perhaps unnecessarily, 
from common feldspar and cleavelandite ; and the leucite or amphigene, 
chiefly from Vesuvius, in separate crystals of various sizes and degrees 
of transparency, massive, embedded in pyroxenic and other lavas. 
* The top of the small octagonal table, standing near Case 30, is a slab of opales- 
cent feldspar from Finland. 
