MINERALOGY. 
The system of Brongiiiart includes sub- 
stances which are not treated of by writers 
on mineralogy, and is divided into five 
classes. The first contains those substances, 
excluding the metals, which are combined 
with oXygen ; it contains two orders ; the 
first including air and water ; and the se- 
cond the acids. The second class treats of 
saline bodies, and comprehends the alka- 
line and the earthy salts. The third class, 
containing stones, includes the hard, the 
magnesian, and the argillaceous stones. 
The fourth class contains the combustible 
substances, viz. the compound and simple. 
The fifth class includes metals, which are 
separated into the brittle and the duc- 
tile. 
The system of Werner, as given by Pro- 
fessor Jameson, has been chiefly adhered to 
in this work, and a detail of the several ge- 
nera will be found in their alphabetical or- 
der; it will therefore be suflficient, in this 
place, to give an outline of his system. 
He has arranged the characters of mine- 
rals under four divisions : the external; the 
internal or chemical ; the physical ; and the 
empirical. To the first belong the charac- 
ters drawn from those properties which are 
obvious to the senses, such as colour, lustre, 
transparency, form, texture, hardness, and 
specific gravity : to the second, those which 
are derived from the chemical composition, 
or discovered by any chemical change 
which the mineral suffers : to the third are 
referred those characters which are afford- 
ed by certain physical properties, as elec- 
tricity or magnetism ; and to the fourth, a 
few characters derived from circumstances 
frequently observed with regard to a mine- 
ral, as the place where it is found, or the 
minerals by which it is usually accompa- 
nied. 
Of these divisions, the external charac- 
ters are considered as the most important, 
and it is chiefly with regard to them that so 
much labour has been employed on the lan- 
guage of mineralogy. The first property is 
colour, which, though but seldom highly 
characteristic, is one of the most obvious 
characters. It varies frequently in the 
same species, and is liable to change by 
very trivial foreign circumstances; it always 
enters, however, into the description. To 
give precise ideas of the different shades of 
colour, M'^erner has fixed on certain princi- 
pal or standard colours, to which the subor- 
dinate sliades are referred; defining them 
by means of an epithet, either expressive of 
the intermixture of one of the principal 
colours with the other, or derived from 
some substance familiarly known, the co- 
lour of which is constant. The principal 
characters are white, grey, black, blue, 
green, yellow, red, and brown. Of these 
are numerous subordinate colours, as blue- 
ish-grey, greyish-black, &c. These are not 
alw'ays well marked, but incline to, aie in- 
termediate, or pass into each other. The 
shade of colour is of different intensities, as 
dark, deep, light, and pale. Besides these, 
other varieties are introduced, as dotted 
striped, zoned, &c. and the colour is varied 
by scraping the surface, affording a charac- 
ter called a streak. 
Lustre denotes the relation which a fos- 
sil bears tp the reflection of the light from 
its surface. According to Werner, “ re- 
splendent” denotes the highest degree of 
lustre, which is such as to be seen at a con- 
siderable distance; “shining” is applied 
when the lustre, though perceived at a dis- 
tance, is not so tvell observed as on a near 
approach ; “ glistening,” when it is percep- 
tible only at a very short distance; “ glim- 
mering,” when some of the minute parts 
only of a surface reflect a weak light; and 
“dull,” when lustre is entirely wantin". 
Different kinds of lustre are also marked, 
as the metallic, adamantine, vitreous, waxy* 
pearly, and resinous. * 
Transparency is denoted by different de- 
grees and terms ; “ transparent ” is applied 
where objects can be distinctly perceived 
through the interposed substance ; “ semi- 
transparent,” where objects are seen, but 
not distinctly, and this only through thin 
pieces ; “ translucent,” when light is in 
some measure transmitted, hut objects can- 
not be observed ; “opaque,” when no per- 
ceptible light is transmitted; connected 
with transparency is refraction, which, in 
the greater number of minerals, is sin*de 
but in some double, the latter giving a d'ou- 
ble image when an object is surveyed 
through them. 
Form, the most important, perhaps, of 
the external characters, includes the figures 
of their crystals, and the various particular 
shapes which many of them, even in their 
imcrystallized state, often assume. The 
texture of fossils, as discovered by their 
fracture, affords another and very impor- 
tant discriminating character. The fracture 
may either present a surface continuous or 
uninterrupted ; or it may present a surface 
composed of an aggregation of distinct 
parts, by which the continuity is more or 
less broken. The former is denominated 
