distinguish their sound, and by the smell and 
taste the qualities which these two senses in- 
dicate. 
In friable minerals, external shape, lustre, 
i aspect of particles, soiling, and degree of fri- 
ability, are to be attended to. 
In fluid minerals the lustre, transparency, 
and fluidity, are principal objects to be re- 
garded. 
The specific external characters of mine- 
rals are founded on the distinctions and varie- 
ties ot the two great generic divisions. And 
first, of colours, the names of which are de- 
rived from certain bodies in which they most 
•generally occur, either in a natural or arti- 
ficial state, or from different mixtures and 
•compositions of both. 
I. Colour. 
1. White. This may be snow-white, red- 
dish-white, yellowish-white, silver-white, 
greyish-white, greenish-white, milk-white, or 
tin-white. 
2. Grey. Lead-grey, blueish-grey, pearl- 
grey, reddish-grey, smoke-grey, greenish- 
grey, yellowish-grey, steel-grey, and ash- 
3. Black. Grevish-black, brownish-black, 
dark-black, iron-black, greenish -black, and 
blueish-black. 
4. Blue. Indigo-blue, Prussian-blue, la- 
vender-blue, smalt-blue, sky-blue. 
5. Green. Verdigris-green, celaden-green, 
mountain-green, emerald-green, leek-green, 
apple-green, grass-green, pistachio-green, as- 
paragus-green, olive-green, blackish-green, 
canarv-green. 
6. Yellow. Sulphur-yellow, lemon-yel- 
• low, gold-yellow, bell-metal -yellow, straw- 
yellow, .wine-yellow, Isabella-yellow, ochre- 
yellow, orange-yellow, honey-yellow, wax- 
yeilow, brass-yellow. 
7. Red. Morning-red, hyacinth-red, 
brick-red, scarlet-red, copper-red, blood- 
red, carmine-red, cochineal-red, crimson- 
red, columbine-red, flesh-red, rose-red, 
peach-blossom-red, cherry-red, brownish- 
red. 
8. Brown. Reddish-brown,- clove-brown, 
hair-brown, yellowish-brown, tombac-brown, 
wood-brown, liver-brown, blackish-brown. 
Besides these distinctions, colours may be 
clear, dark, light, or pale ; they may have a 
tarnished appearance, a play, a "change- 
ability, an iridescence, an opalescence, a 
permanent alteration, and a delineation of 
figure or pattern, such as dotted, spotted, 
clouded, flamed, striped, veined, dendritic, 
or ruiniform. 
II. Cohesion of Particles. 
Minerals are divided into, 1. Solid, or 
such as have their parts coherent, and not 
easily moveable ; 2. Friable, or that state 
of aggregation in which the particles may be 
overcome by simple pressure of the finger ; 
and, 3. Fluid, or such as consist of particles 
which alter their place in regard to each other 
by their own weight. 
1 . Solid Minerals. 
External aspect has three things to be re- 
garded, 1.1 he shape; 2. The surface; and 
3. The lustre. The external shape again 
Vol. II. 
mineralogy. 
may be common, particular, regular, or ex- 
traneous ; and hence arise the specific dif- 
ferences. 
1 . The common external shape may be mas- 
sive ; disseminated coarsely, minutely, or 
finely ; in angular pieces, sharp-cornered or 
blunt-cornered ; in grains, large, coarse, 
small, fine, angular, flat, round; in plates, 
thick or thin ; in membranes or flakes, thick, 
thin, or very thin. 
The particular external shape may be long- 
ish, as dentiform, filiform, capillary, reticu- 
latic, dendritic, coralliform, stalactitic, cylin- 
drical, tubiform, claviform, or fruticose; 
roundish, as globular, spherical, ovoidal, sphe- 
roidal, amygdaloidal, botryoidal, reniform, 
tuberose, or fused-like ; flat, as specular, or 
m leaves ; cavernous, as cellular in various 
forms, with impressions, perforated, corrod- 
ed, amorphous, or vesicular; entangled, as 
ramose, &c. 
In the regular external shape or chrystalli- 
zation are to be regarded its genuineness, ac- 
cording to which it may be either true or 
suppositious ; its shape, made up of planes, 
edges, angles, in which are to be observed 
the fundamental figure and its parts, the 
kind of fundamental figure, the varieties of 
each kind of fundamental figure, with their 
accidents and distinctions, and the alterations 
which the fundamental figure undergoes by 
truncation, by bevelnient, by acumination, 
or by a division of the planes. There are a 
variety of figures under each of these subdi- 
visions. 
It must be remarked also that the external 
shape may be extraneous, or derived from 
the animal and vegetable kmgdoms, as in 
fossils and petrifications. 
2. The external surface contains several 
varieties of distinctions. It may be uneven, 
granulated, rough, smooth, or streaked in 
various ways and directions. 
3. The external lustre is the third generic 
external character, and is of much importance 
to be attended to. In this we have to con- 
sider the intensity of the lustre, whether it is 
splendent, shining, glistening, glimmering, 
or dull ; next the sort of lustre, whether me- 
tallic or common. The latter is distinguish- 
ed into semimetallic, adamantine, pearly, re- 
sinous, and vitreous. 
Aspect of the Fracture of solid Minerals. 
Aftui- the external aspect, the fracture 
forms no inconsiderable character in mine- 
rals. Its lustre mav be determined as in the 
external lustre; but the fracture itself admits 
of great varieties. It may be compact, 
splintery, coarsely splintery, finely splintery, 
even, conchoidal, uneven, earthy, hackly! 
It the fracture is fibrous, we are to consider 
the thickness of the fibres, if coarse or deli- 
cate; the direction of the libres, if straight or 
curved; and the position of the fibres, If pa- 
rallel or diverging. 
In the radiated fracture we are to regard 
the breadth of the rays, their direction, their 
position, their passage or cleavage. In the 
foliated fracture, the size of the folia, their 
degree of peifection, their direction, position, 
aspect ot their surface, passage or cieavage, 
and the number of cleavages, are to be noted! 
Hie shape of the fragments may also be 
eery vaiious-regcilar, as cubic, rhomboidal, 
trapezoidal, &c. or irregular, as cuneiform, 
splintery, tabular, indeterminately angular. 
C c 
2dl 
Aspect of the distinct Concretions. 
1 he shape of the distinct concretions forms 
very prominent external characters. They 
may be granular , different in shape, or in mag- 
nitude ; they may be lamellar, distinct, con- 
cretious, differing in the direction of the la- 
mella - , in the thickness, with regard to shape, 
and in the position. 
1 he surface of the distinct concretions 
may be smooth, rough, streaked, or uneven ; 
as for their lustre, it may be determined in 
the same manner as the external lustre. 
General Aspect as to Transparency. 
Minerals, as is well known, have different 
degrees of transparency, which mav be con- 
sidered among their external characters. 
They may be transparent, semitransparent, 
translucent, translucent at the edges, or 
opaque. 
The Streak. 
The colour of this external character may 
be either similar or different. It is pre- 
sented to us when a mineral is scraped with 
the point of a knife: and is similar, when the 
powder that is formed is ot the same colour 
with the mineral, as in chalk; or dissimilar or 
dilferent, as in cinnabar, orpiment, &c. 
The Soiling or Colouring 
Is? ascertained by taking any mineral sub- 
stance between tiie lingers, ' or drawing it 
across some other body. It may soil strongly, 
as in chalk, slightly, as in molybdena, or not 
at all, which is a quality belonging to most of 
the solid minerals. All the preceding ex- 
ternal characters are recognized by the eye. 
External Characters from the Touch. 
These are eight in number, and are not 
destitute of utility to the mineralogical stu- 
dent. 1. Hardness; 2. Tenacity ; 3. Fran* 
gibihty ; 4. Flexibility ; 5 . Adhesion to the 
tongue; 6. Unctuosity ; 7. Coldness; 8. 
Weight. 
Hardness may be tried by a capacity to 
resist the file, yielding a little to it, by bein°- 
semi-hard, soft, or very soft. Tenacity has 
different degrees, in substances being brittle 
sectile or mild, or ductile. The frangibility 
consists in minerals being very difficultly 
frangible, difficultly frangible, easily francri- 
ble, or very easily frangible. The flexibility 
is proved by being simply flexible, elaslidy 
flexible, commonly flexible, or inflexible. 
I he adhesion to the tongue may be strongly 
adhesive, pretty strongly, weakly, very 
weakly, or not at all. Unctuosity' may be 
meagre, rather greasy, greasy, "or very 
greasy. Coldness is subdivided into cold" 
pretty cold, rather coid. Weight mav be 
distinguished into swimming or supernatant- 
fight, rather light, heavy, very heavy. The 
three last divisions from the touch, are in the 
Wernerian system regarded as anomalous • 
but they seem property to be classed under 
this head. 
External Characters from the Sound or 
Hearing. 
The different kinds of sound which occur 
in tiie mineral kingdom are, 1. A ririo-in K 
sound, as in native arsenic and thin splinters 
ot horn-stone; 2. A grating sound, as j n 
fresh-burnt clay; 3. A creaking sound as 
that of natural amalgam. 
