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longer duration. Some regard it as a maxim in literature,
that a book should be as complete in itself as possible ; and a
reference to a work, which he can neither procure nor read,
would contribute little to the instruction of the learner. The
candid will likewise consider the entire novelty of the plan 5


which, while it required a minute attention to the congruity
of the parts, must also, like a new road, lead to mistakes
and deviations, perhaps more numerous than the author can
conceive ; and which, if pointed out with benevolence, he
will be ever ready to correct with gratitude. " Those who
have gone before us," says an ancient classic, " have done
much, but they have not finished ; much labour still remains,
and much will remain ; nor will an occasion be wanting of
adding somewhat even to authors who shall be born after a
thousand ages."*

* Sane multura illi egerunt, qui ante nos fuerunt, sed non peregerunt;
multum adhuc restat operis, multumque restabit, nee ulli nato post mille
secula pnecludetur occasio aliquid adjiciendi. SENECA.




Mode I. Siderite 2

II. Basalt . 17

III. Basaltin 32

IV. Basalton 72

V. Porphyry 75

VI. Porphyrin 87

VII. Porphyron 88

VIII. Porphyroid ib.

IX. Amygdalite 89

X. Iron-stone 95

XI. Jasper 99

XII. Slate 105

XIII. Mica Slate 122

XIV. Sideromagnesian Rocks 126

XV. Siderous Intrite 132

XVL Siderous Glutenite 135


Mode I. Quartz 146

II. Keralite .-*. 153

III. Felspar 157

IV. Felsite 16O

V. Granite 177

VI. Granitin 201

VII. Graniton 202

VIII. Granitel 203

IX, Granitoid ,...,. ,,,,,, ,,.,,, 209

TOL, i.


Mode X. Granitic Porphyroid p. 210

XI. Gneiss 211

XII. Pitch-stone 218

XIII. Siliceous Intrite 220

XIV. Siliceous Glutenite . 223


Model. Alum Rock 242

II. Clay Slate 249

III. Clay Rock 269

IV. Wacken 273

V. Smectite 275

VI. Iconite 278

VII. Argillaceous Intrite 281

VIII. Argillaceous Glutenite 283


Mode I, Talc 1 301

II. Talcous Slate , 309

.111. Micarel Slate 312

IV. Steatite 313

V. Ottite 327

VI. Serpentine 334

VII. Saussurite 354

VIII. Green Granitel 362

IX. Magnesian Limestone 363

X. Green Marble 366

XI. Magnesian Intrite 372

XII. Magnesian Glutenite 373


Mode I. Marble 380

II. Konite 427

III. Limestone ,.... 441

IV. Alabastrite . 458


ModeV. Lime-slate p. 467

VI. Coral Rock 473

VII. Marlite 475

VIII. Orsten 480

IX. Gypsum 482

X. Alabaster 498

XI. Chalk 504

XII. Tufa 509

XIII. Calcareous Intrite 519

XIV. Calcareous Glutenite 520


Mode I. Graphite 544

II. Anthracite 552

III. Coal 563

JV. Lignite ., , 583




P. 21, Note. Compare Ferrara's accounts in Dom, XII.
85, Note. Verd d'oeillet may be the peculiar light sea
green of the grass, or leaves, of some pinks or car-

98, 1. 13. For Eisenthorn, read Eisenthon.
J06, L 21. The analysis of Slate and Mica Slate, by Dau-
buisson, is in the Journ. de Ph. Juin 1809.

Silex 48, 6

Argil 23, 5

Magnesia 1, 6

Peroxyd of Iron 11, 3

Oxydated Manganese 5

Potash 4, 7

Carbon 0, 3

Sulphur 0, 1

Water and Volatiles 7, 6



This he compares with Klaproth's analysis of Mica,
which yielded, Silex 47, Argil 20, Oxyd of Iron 15,
of Manganese 2, Potash 15.

137- Col. Imrie (Tr. Wern. Soc. i. 454), says, the glutenite
near Stonehaven consists of pebbles of quartz and
porphyry, with some of jasper, hornblende, horn-
stone, cemented by a reddish brown ferruginous
clay, mixed with minute particles of quartz and
mica, but which only fills the intervals. At Oban


the cement appears a blackish grey indurated sand,
composed of argil, fine sand, black oxyd of iron,
and is slightly coherent. It is singular that this
glutenite is vertical on the E. and horizontal on
the W.

P. 155, Note. The Black Forest Mountains form another

167, Note. For ava, read lava.

374, Note, for Voyage, read Journey.

345, 1. 8. For Marbois, read Marbore.


64. Compare the sites of Miagite in the Appendix.

100, 1. 2. For resemble to, read resemble.

221, 1. 2. For Roy. read Roz. that is, the Journ. de Ph.
by Roz i ere.

267. The following account of the fall of Rosenberg may
not be unacceptable.

" On the 2d September, 1806, at five in the evening, the
Knippenouhl Rock, which formed the summit of Mount Ro-
senberg, was on a sudden detached from its situation ; and at
the same time part of the mountain, of several feet thick, on
the western side, and about 280 feet thick on the east side,
gave way, and fell into the valley which separates the lake of
Zug from that of Lauwertz. One part of the mountain fell
into the lake of Lauwertz, which caused such an agitation in
the waters of the lake, that they overthrew a number of
houses, chapels, mills, &c. along the southern shore. Up-
wards of one thousand persons were the victims of this cala-
mity. A society of thirteen travellers were on the road from
Arth to Schwitz : nine, who walked first, perished ; the other
four escaped. In this convulsion enormous pieces of rock
were carried through the air to prodigious distances. The
lake of Lauwertz has lost above a quarter of its extent. That
rich plain which was so beautiful, now presents a mountain
of near one hundred feet in height, a league and a half in


length, and as much in breadth. The villages of Goldau
and Rothen, consisting of one hundred and fifteen houses 5
that of Busingen, of one hundred and twenty-six j and that
of Kuslock, have totally disappeared. Of Lauwertz, which
lost twenty-five houses, there remain ten buildings, all much
damaged. Twenty years since general PfyfFer predicted this
catastrophe, from the knowledge that he had of the nature of
the mountain. A professor of Schwitz said, that above Spiets-
fleu was a sea of water, which had undermined the rock for
several years, and that below there was a cavern of great
depth, where the waters were engulphed. The quantity of
water which has fallen during the preceding years has hastened
this catastrophe, and the rains of some weeks past have de-
cided it. On the 10th eight hundred persons were employed
in digging for the bodies of those who were destroyed by the
falling of the mountain at Schwitz. In forming a channel to
draw off the waters, between thirty and forty labourers were
swallowed up by a torrent of muddy water, which broke in
upon them suddenly." *

Besides the plates and description published at Paris, there
are three large views drawn and engraved by Wiebel, a Swiss
artist, which the author has seen. The effect is not that of a
fallen cliff, as in granitic mountains, but that of masses of
rock, detached and thrown down a gentle declivity, with such
impetus as to overwhelm every obstacle, and spread to an
amazing distance.

P. 306, 1. 5. For tufa, read tufo.

401, 1. 16. For PRODUCTION, read PRODUCTIONS.
428, Marginal indication. For Former rocks, read Forms

* Annual Reg. 1806, p. 448.





THE name sidegea, as not unusual iii
compounded words, is abbreviated from
two Greek terms, signifying iron and earth.
The reasons for the introduction of this
grand division, adopted in substance by
the most eminent geologists, have already
been given. Iron acts so important and



radical a part in the constitution of our
planet, that it deserves to be viewed under
various aspects, not only as a metal, but
as an earth, strongly impregnating most
of the others, and often exerting a pre-
dominating influence. For as, since the
recent discoveries, many earths have been
known to assume the form of metals, so
thefe can be no impropriety in considering
this universal metal under the form of an

When a substance contains more than
twenty-five parts in the hundred, or, in
other words, one quarter, of iron, it may
be worked as a metallic ore, and arranged
under that denomination. But in a smaller
quantity it will fall under the present divi-
sion, especially when intimately combined
with the other earths. It was by metallo-
gists considered as a calx, or latterly called
an oxyd. Mr. Kirwan*, who has rightly
added calces of iron to his description of
the earths, says, that they are formed of
that metal, combined with different pro-

* Min. i. 17.


portions of pure air, and frequently of water
also and fixed air.

" One hundred parts metallic iron are
capable of taking up 66 or 70 of pure air.
When 100 parts iron contain but 40 of this
air, the compound is still magnetic/' His
table of the fusibility of the simple earths
presents some curious experiments on the
mixture of calcined iron and rust of iron,
with other substances, which show the
power of this metal. Even when it only
amounts to four parts in the hundred, it
sensibly influences the compound.

Sidegea, or siderous earth, is so generally
diffused, that almost every mineral sub-
stance derives its colour from it, from a
pale blue to the deepest red. Animal sub-
stances contain it ; and it exists in the ve-
getable kingdom, even in plants apparently
supported merely by air and water. It
would appear that even the atmosphere
abounds with atoms of iron, whence per-
haps the meteoric stones.



Texture, generally crystalline, as in the saline
or primitive marbles; the prisms sometimes in-
tersecting each other, so that it becomes difficult
to determine their figure*. The grains are
sometimes so small that it assumes a compact
appearance, in which case it passes into basalt.

Hardness, basaltic, sometimes only marmoric.
Fracture commonly foliated, sometimes radiated,
tough. Fragments rather sharp.

Weight, siderose : sometimes approaching the

Lustre, splendent, shining, between vitreous
and pearly. Opake; the green sometimes trans-
lucent on the edges.

Colour generally black, sometimes of a green-
ish grey.

Siderite sometimes composes entire mountains,
but more commonly occurs disseminated, or
forming veins or nodules, in granite ; or beds in

This important substance, which is so widely

Hornblende, disseminated, is the hornblende of the German

miners; a barbarous term, which, like many

* The crystals of siderite are of an oblong quadrilateral form,
while those of mica are hexagonal.


others, had passed into the science before it be-
came classical*.

" Mountains of black hornblende exist in Si- sites.
beria, Renovantz, 32 : as the Tigereck, 4 Nev.
Nord. Beytr. 192; and others mentioned by
2 Herm. 271. Frequently mixed with quartz,
mica, or felspar, or shorl, and either greenish or
black. Ibid. But it is more commonly found in
mighty strata, as in Saxony ; or still oftener as a
constituent part of other primeval rocks, as in
syenite and grunstein ; sometimes in layers in
gneiss, or granular limestone, or argillite; and
sometimes in horn porphyry. 2 Berg. Jour.
1788. 503. 1 Lenz. 325. 1 Emmerling, 325;
or in the gullies of granite. Herm. Ibid. Horn-
blende slate was observed among the primeval
rocks on the ascent of Mont Blanc, 7 Sauss.
241, 253, mixed with plumbago; Ibid, and on
its summit, Ibid. 289."

" Strata of schistose hornblende occur some-
times in gneiss, as already mentioned. At Mil-

* Blend, in German, sometimes implies Hind, sometimesjfa/se
or deceitful ; but the name seems rather to have arisen from its
having the appearance of blende, an ore of zinc, which was also
called pscudo galena. Blend, or in modern German Hind, never
has the final e : and there would be no sense in Hind horn. But as
the substance much resembles black blende, and, when struck, often
crumples like horn, the etymology is very clear. A French writer
rightly translates it Blende de come. Hornstein and Hornsilver arc
translucent as horn.


tiz a stratum of it has been found over granular
limestone. Voigt Prack. 33. In Lower Silesia
it has been found on syenite. 4 Berl. Beob.
349. Granite sometimes rests on it. 2 Berg.
Jour. 1790, 300. Voigt Mineral. Abhaudl. 25.
Hence there can be no doubt of its being a pri-
mitive stone. A mountain of it exists in Tran-
sylvania; 1 Bergb. 40. Nay, granite has been
found in it. 1 Berg. Jour. 1789, 171. It is fre-
quently mixed with mica, more rarely with
visible quartz : Emmerling*."

Patrin observed in Siberia many mountains
entirely composed of siderite, and containing
masses or veins of granite; while reciprocally
the mountains of granite often present veins and
masses of siderite f. These accidents are parti-
cularly frequent in that part of the Altaian
mountains which approaches the river Irtish,

It also abounds in Bohemia, Saxony, Tyrol,
and many other countries, not to mention the
isles of Arran, Col, and Tirey; the district be-
tween Lochlomond and Dunkeld,and other parts
of the Highlands of Scotland ; and also near
Holyhead in Wales.

Saussure describes, 674, a strange mixture
of massive granite with a grey heavy rock, which

* Kirwan Geol. Ess. p. 181.
f Min. i. 127.


on the outside appeared of a rust-colour. This
is evidently a siderite, of which the iron is de-
composed. He justly observes, that both must
have crystallised together, and of course siderite
must be as ancient as granite*.

The rocks of siderite are by Werner classed
among the Primitive Traps, which he divides into
the common, the granular, and the schistose;
with two mixtures, siderite with felspar and with
mica. The admixtion of mica and pyrites is
by Daubuisson regarded as characteristic of the
primary traps. That of siderite and felspar Primitive trap,
constitutes the primitive grunstein of Werner,
including the common, the porphyritic, the
grunstein porphyry, the green porphyry of the
ancients, and grunstein slate ; which latter has,
according to Daubuisson, been called horn-
sckiefer. Some of these primitive traps have
been arranged under the large and vague deno-
mination of corneenne, roche de corne, pierre de
comedy by the French mineralogists; and even
by Saussure, who tells us, 122.5, that when the
corneenne, or pierre de corne, has marks of crys-
tallisation, it assumes the name of hornblende.
But as the stones, confessedly called basalts by

* The summit of the Dome du Goute consists of siderite in a
State of decomposition. Id. IQSO.
f* La pierre cornde is petrosilex.


the ancients, often present marks of crystal^
lisation, being sideritic rocks or primitive traps,
they shall be considered under that division.
Wad, in his account of the Egyptian minerals in
the Borgian Museum*, observes, that the ba-
Ancient basalt, sal tic monuments of the ancients are referable
to two classes; 1. The primitive, consisting of
black hornblende, or siderite, which is some-
times so mingled with veins of felspar, and often
with quartz and felspar, partly rude partly crys-
tallised, that it is in some examples difficult to
determine whether they should be placed among
the basalts, or syenites, of Werner. 2. This
class appears of more recent formation, and in
all respects agrees with the basalt of Werner,
except that it be more hard, owing to the inter-
spersion of minute particles of quartz, being
very similar to the stone with which the ancient
Roman ways were paved, and which is by some
called lava. Some of the ancient basalts there-
fore cannot be distinguished from siderites, as
the ancients were not conversant in the minute
discriminations of modern science : and some
monuments which they would have called ba-
salts, a modern mineralogist would rank among
the black granites. But as the ancients cannot
be our guides in mineralogy, a science to them

* Fossilia JEgyptiaca Musei Borgiani. Velitns, 1794, 4to. p. 7*


utterly unknown, it is sufficient to say, that the
rocks which the acute Werner, and his disciples,
have classed under HORNBLENDE, here appear
under SIDERITE, and some of their TRAPS under
BASALT 5 while the trap of the Swedes, with a
fine grain, is here called BASALTIN. The dif-
ference indeed is rather in the transition ; the
chemical analysis of siderite and basalt being
nearly the same.


Silex 37 Silex 50

Argil 22 Argil 15

Magnesia 16 Magnesia 2

Lime 2 Lime 8

Oxyd of iron ... 23 Iron .25

100 100

It scarcely needs to be observed, that in all
substances the proportion of ingredients varies
according to circumstances.

In general therefore where the substance has
a crystallised and silky appearance, it must be
classed among the siderites ; but when it wears
a dull or earthy aspect, it belongs to the basalts,
though in the latter shining crystals of siderite
may be interspersed.

When mica alone is found in a substance, it
cannot alter the denomination, for, as Mr. Kir-
wan has observed, there is scarcely a mineral in


which it may not be found. But the mixture of
siderite with felspar deserves a distinct appel-

Onmstein. lation. The term grunstein or green stone, used
by Werner, has been deservedly ridiculed, as
alike vague and barbarous. He borrowed it
from the Swedes, whose grunstein was really
green. It is further objectionable, as he extends
it to green porphyry, and other mixtures of
earthy trap or basaltin. As many new appel-
lations are wanted, to distinguish with brevity
and precision the different kinds of rocks, it is

Waiierite. proposed to call this mixture WALLERITE, in
honour of Wallerius, the great Swedish father
of mineralogy. The other kinds of grunstein
are arranged after basalt; as by their earthy
texture they differ greatly from the former : nor
can the black and green porphyry of the an-
cients, classed by Werner under this head, be
considered as having any other basis than com-
mon trap.


Aspect 1. Uniform. Black siderite of Egypt.
This substance is more generally found mingled
with granite ; but scarabcd and other small sculp-
tures sometimes occur in it, and sometimes in that
ore of iron called hematites*.

* See Wad, p. 8 and 32.


Black siderite from Mount Sinai. Given to the
author by Roziere, a skilful mineralogist, who
accompanied the French expedition.

Compact siderite, from the isle of Col, Scot-

The same, from the iron-mines of Sweden.

The same, of a brownish and grey colour, from

Green siderite, from Sweden.

Saussure mentions, 1824, beautiful beds of
black siderite, in one of which an excavation had
been made to extract crystal.

Aspect 2. Mingled. Black siderite, with mi-
ca, from Egypt.

The same, with olivine, from Egypt.

The same, with gold and silver, or with elec-
trum, a natural mixture of these two metals, from
Kongsberg in Norway.

Green siderite, with garnets, from Sweden.

The same, intermixed with iron ore, from Salz-

The same, with hard clay, from Vesuvius.

The same, with pyrites, from Arindal in Nor-

The same, from Salberg in Sweden.

The same, from the iron-mines of Dognaska, in
the Bannat of Hungary.


The detached crystals of siderite, and what is
called Labradore hornblende, or schillerspar, if
it be not another substance, are properly topics of
gemmology, or lithology, and not of petralogy,
as they never occur in the form of rocks. It may
be proper to observe, that siderite is called by
many French writers schorl en masse, and some-
times schorl spathique.

The real grunstein of the Swedes is a mixture
of siderite and mica, sometimes with particles of
quartz *.

Fine grained siderite, with mica, from Upland.

The same, large grained, with quartz, from

The same, with spots of steatite, from Taxas in


This substance, the hornblende slate of the Ger-
mans, is often found in gneiss, as already men-
tioned; but it is often joined with compact si-
derite ; and, with a greater mixture of magnesia,
passes into chlorite slate : for between siderite,
chlorite, and actinote, there is a near connexion :
whence Saussure argued that chlorite is merely

* Wall. i. 436. Whence it appears that it was also called
Binda and Jernbinda : the Saxum ferreum of our author.


the earth of green hornblende. Compact and slaty
siderite also frequently occurs, in large masses, in
common slate, a kindred rock.

Aspect 1. Uniform. Schistose siderite, of a
beautiful silky texture, from Kongsberg in Nor-

Schistose siderite, from Holyhead.

The same, delicately waved, from Norway and
the Highlands of Scotland.

Aspect 2. Mingled. Schistose siderite, with
garnets, from Kongsberg.

The same, with native gold and silver, from
the same.

The same, with particles of quartz, from Saxony.

Schistose siderite in divergent rays, sometimes
of a fascicular sometimes of a starry form, from
the Alps, where it is often imbedded in granular
felspar. This rock will seldom admit of a polish,
otherwise it might rival the Miagite, the arborescent
granitel found in the ruins of Rome, and other
splendid and celebrated mixtures of felspar and
siderite, which are here classed amongst the ANO-

Saussure describes different kinds of schistose
siderite in the following terms :

e The schistus composed of hornblende and


felspar is very common upon the banks of the
Isere, and this is not extraordinary, as there are
even entire mountains of it in Dauphiny, which I
have myself seen. The famous silver mine of
Challenches, into which I descended, is in a moun-
tain of this kind. The varieties of this rock are
extremely numerous; we find it with leaves sin-
gularly distorted, or bent in zigzag. It sometimes
occurs with thick leaves, and at others as thin as
paper. In some varieties, the leaves of pure and
coloured hornblende, alternate with leaves of white
and pure felspar ; in others, these two substances
are almost confounded; in others, in short, the
leaves are interrupted either suddenly or by gra-
dations. There are also frequently found knots
or detached pieces of white felspar, confusedly
crystallised, and often mixed with quartzose parts.
It is curious to observe, when these knots are of
irregular shapes, the exactness with which the
schistose leaves follow all the convolutions of the
knots, and form a kind of fortifications around

" The hornblende varies in its colour ; some-
times black and brilliant, sometimes inclining to
green, at others brown or grey ; its form some-
times presents pretty regular crystals, especially
in schisti, whose leaves are straight ; and at other
times thin plates, almost as brilliant as mica,


without any appearance of a regular form. It is
likewise more or less fusible under the blow-pipe.

" The felspar also varies by its white colour
more or less pure, and inclining sometimes to
a green or rosy hue ; and by its form which, at
one time, presents pretty regular rhomboidal la-
minae, at others a crystallisation quite confused
in small granular masses, like statuary marble.
There is sometimes seen in the leaves, as in the
knots, a mixture of a little quartz. The felspar
which enters into the composition of this schistus
is commonly of that kind which I have termed
feldspath sec, or dry felspar ; I have however seen
but only one piece, of which the felspar was gras,
or unctuous." 1586.

He also mentions

2227. A green rock, which he would formerly
have called roche de corne, but must now refer to
the hornblende slate of Werner : and,

1971. A gneiss, composed of laminar siderite
and felspar, on the ascent of Mont Blanc.

227 1. A slate of fine scales of mica and horn-
blende, sometimes in level plates, sometimes un-
dulated. It is of an olive-green colour, acts faintly
upon the magnet, and makes a hasty effervescence
with acids ; a proof that it contains some cal-
careous particles.

2131. Near Macugnaga, brilliant hornblende


slate, in large redoubled layers, so as to form?

masses three or four inches in thickness, enchased


in dull white quartz.

1 822. Beautiful rocks of granular felspar,
with long irregular crystals of siderite, which
sometimes assume the form of sheaves or di-

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