58 
NATURAL HISTORY. 
[north 
of Vesuvius, and the greater part of the scapoliie, the paranthine, the 
dipi/re, the nuitallite, the hergmannite; substances which, together with 
several others provisionally placed in this glass Case, stand in need of fur¬ 
ther 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, and particu¬ 
larly from Vesuvius, where it occurs in small, but brilliant and transpa¬ 
rent six-sided prismatic crystals; to this also appear to belong some 
varieties of mica called ruhcllane, and the liihia-mica, which besides 
the beautiful peach-blossom, red, violet, greenish-grey, and white scaly 
varieties known by the name of lepidolite, (some varieties of which, how¬ 
ever, are referable to the silicates combined with fluorides, in Case 58 A,) 
from Rdzna in Moravia, likewise comprises several large-foliated va¬ 
rieties of what was formerly considered as common mica, such as that 
from Zinnwald in Bohemia and Altenberg, accompanied by apatite, tin¬ 
stone, and topaz. 
The species and varieties of the talcose substances are likewise 
very imperfectly understood. Among the specimens of talc in this 
glass Case may be specified the common or Venetian (which enters 
into the composition of cosmetics), and the indurated talc; to the former 
of w’hich may probably be referred the green radiated talc fi'om Siberia, 
composed of distinct groups of small diverging laminae, and which is 
known under the name of pyrophyllite; — chlorite, crystallized in ag¬ 
gregated, small, modified rhombic prisms ; the earthy and foliated 
varieties, coating crystals of octahedral magnetic iron-stone, &c. ; 
chlorite slate; — the scarce leucliimhergite from the Ural, the composi¬ 
tion of which appears to approach near to that of chlorite; — pinitey 
crystallized in regular hexagonal prisms, and gieseckite, from Green¬ 
land, W’hich appears to be a variety of this species. — Fahlunite or 
triclasite, with the related voeisdte, from Fahlun in Sweden. 
Case 33. This and part of the follown.g Case chiefly contain sub¬ 
stances related to hornblende or amphibolic minerals, among which may 
be specified the basaltic and common hornblende, including the parga- 
site ; — the actinolite or strahlstein (divided by Werner into the glassy, 
common, and fibrous varieties); — the grammatite or tremolite (so caned 
from Val Tremola, where, however, it is not found), among the speci¬ 
mens of which are the fine, fibrous varieties, resembling asbest; the 
glassy tremolite, in dolomite and granular limestone, &c — Arfvedsonite 
— raphilite, &c. 
Case 34. Part of this Case is occupied by the mineral substances 
called asbestine, many of which pass into some of the varieties of hom- 
olende; others, both asbest and amianth, are modificatiojis of the state 
of aggregation of ditferent amphibolic substances, and to these Erei- 
thaupt also refers his kvmatine, metaxite, peponite, and pycnotrope. 
Among them may be observed specimens illustrative of the transition 
from a very close to a loose-fibrous structure ; — several varieties of the 
Jiexible asbest or amianth, with some antique incombustible cloth, 
