68 natural history. (Minerals.) [north 
nite, gismondine , abrazite , and also 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 remarkable 
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; an da 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 ; albite or cleavelandite , 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 a*mphigene, 
chiefly from Vesuvius, in separate crystals of various sizes and degrees 
of transparency, massive, embedded in pyroxenic and other lavas. 
Case 31. Other mineral substances of the preceding section here 
deposited, are, the baulite , the triphane or spodumen and th epetalite: in 
which latter substance lithia was first discovered by Arfvedson;—the 
nepheline, from Mount Vesuvius, with which are now combined the 
davyne of Monticelli, and several varieties of the elceolite or fettstein of 
Werner;—the wernerite, under which name, formerly confined to some 
varieties of common and compact scapolite, are now by most mineralo- 
gical writers united the meioniie of Vesuvius, and the greater part of 
the scapolite , the paranthine , the dipyre , the nuttallite , the bergmannite, 
the rosellite, from Aker, and the amphodelite; substances which, together 
with several others provisionally placed in this and the preceding glass 
Case, stand in need of further investigation as to their chemical and 
crystallographical characters. 
Case 32 contains micaceous and talcose substances. Our imperfect 
knowledge of the optical properties and chemical constitution of many 
varieties of the former, does not admit of their being arranged according 
to those distinctive characters ; such varieties as have been more closely 
examined in this respect, may be divided into potassa-mica (by far the 
most common), which has two axes;— magnesia-mica , which has but one 
axis: in characteristic specimens from various localities, particu- 
* The top of the small octagonal table, standing near Case 30, consists of a slab 
opalescent feldspar from Finland. 
