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verging rays. The base of granular felspar has
been mistaken for a sandstone.

2144. Sheaves of black hornblende, two or
three inches in diameter, forming a most beautiful
effect on a white gneiss.

164. Siderite, in the form of a sheaf, or rather
fan, on granular quartz, or rather felspar.

1954. Siderite mixed with calcareous parti-
cles, ramifying alternately with quartz.

STRUCTURE III. WALLERITE.
Wallerite.

This rock, as already mentioned, is one of the
primitive grunsteins of Werner, but is here re-
stricted to a mixture of crystalline siderite with
felspar ; the other primitive grunsteins being class-
ed after the basalts, to which they more strictly
belong.

Wallerite from Sweden, of black crystalline
siderite mixed with felspar.

The same, greenish black, from Snowdon in*
Wales.

The same, from Mount Sinai.






DOMAIN i. SIDEROUS,



17



MODE II. BASALT.

Texture coarse, generally mixed with grains characters,
of quartz or felspar ; it has sometimes a crys-
talline appearance, but the crystals are minute,
so that it appears earthy.

Hardness basaltic. Fracture rather even.
Fragments rather sharp.

Weight siderose.

Lustre shining. Opake.

Colour iron grey, sometimes greenish.

This celebrated substance is one of the traps,
r rather a grunstein, of the Swedes and Ger-
mans; and is by the Wernerian school con-
sidered as of three remote formations, the pri- Formations,
mitive, transitive; and stratiform, also called
floetz, or horizontal.

The basaltic monuments of the ancients are Basalt proper,
allowed by Dolomieu and Faujas, two chief
supporters of the Volcanic system, not to be of
a volcanic nature ; and of course the restriction
of the" name to pretended compact lavas is not
only objectionable, but highly absurd, as trans-
ferring a well-known term to a substance widely
different. Compact lava is so uncommon a sub-
stance, that there was no specimen of it in the
great collection of prince Biscari, at Catania;

VOL. i. c



DOMAIN I. SiDEKOUS.



while Gioeni and other writers on volcanoes
say, that very seldom a piece without pores can
be found, even of a few inches in diameter. A
specimen of compact lava in the British Museum
contains melted garnets ; and is of such an ap-
pearance that no eye can confound it with basalt,
even of the finest texture : yet Faujas, and other
late French writers, persist in restricting the
term basalt to a supposed lava, while they use
the term trap for the real basalt of the ancients ;
which, even by their own volcanic theory, is of
quite a different nature and origin*.

In his description of the Borgian monuments,
as already mentioned, Wad found that those of
basalt might chiefly be referred to siderite or
hornblende : and it is remarkable that the word
basaltes} according to Pliny, signified iron in the
Ethiopic language, as sideros does in the Greek.
The basalts of the ancients are often siderites,
sometimes with veins or grains of felspar or
quartz; sometimes with olivine: the only an-
tique specimen in which leucite occurs having,
as Wad observes, been sculptured at Rome.

Some small Egyptian monuments, however.
occur i n fi ne basalt, here called basaltin : to

* The name lasalt seems subject to a singular fatality of abuse,
the grave Wallerius having, with equal skill, degraded it to com-
mon schorl !



MODE II. BASALT.

which last division the basalt or trap of the
moderns, and pretended lava of the French mi-
neralogists, properly belongs. For the basalt of
Agricola, the trap of Wallerius and Werner, a
substance abundant in the Faroe isles*, Sweden,
Scotland, Ireland, Saxony, Auvergne, Sicily, &c.
may also be traced among the Egyptian and
other ancient monuments ; and as Pliny informs
us that the name of iron-stone was given on
account of its colour and hardness, this appel-
lation must have been yet more applicable to
fine-grained trap than to siderite, which is of a
looser grain and softer cohesion. And while the
ancient denominations are so indistinct that they
have included green fluor, and the fine green
granite of Abyssinia, among the emeralds f, it is
easily conceivable that the term basalt was ex-
tended to two or three distinct rocks, of a colour
and hardness approaching to iron : but even the
basaltin, or fine-grained basalt of the ancients, is
frequently interspersed with minute grains of
quartz or felspar; and monuments of what we
would strictly call trap or basalt are compara-
tively rare. But as it is evident that the basalt

* In the north of Europe. This spelling distinguishes them
from Ferro, one of the Canaries.

t There seems little doubt that the pillars said to be of emerald
were of this sub^tonce.



20 DOMAIN I. SIDEROUS.

of the ancients was more commonly of a coarsfc
grain, and often intermixed with quartz or fel-
spar, it has been thought proper, for the sake of
precision, to confine the term to that substance ;
while the name basaltin is applied to the fine-
grained basalt of the moderns, which frequently
assumes the columnar form, in which shape also
the former sometimes occurs. There is no doubt,
for example, that some of the whirls of the Scot-
ish mineralogists, in which grains of quartz or
felspar are mixed with trap, strictly and properly
belong to the basalts of the ancients.

The dispute therefore concerning the Nep-
tunian or the Volcanic origin of this substance
must more aptly be Considered as having no
concern with the proper BASALT of the ancients,
but with the modern basalt, here called basaltin^
The author of this work is not attached to any
theory, nor does he believe that the facts and
observations are yet sufficiently numerous to.
afford even the semblance of a plausible conca-
tenation ; but he may be allowed to observe, that
though volcanoes are often situated in basaltic
countries, as they of course abound with iron, of
itself inflammable, and yet more with sulphur,
and probably forming the great source of vol-
canic fires ; yet, as there is no proof of any vol-
cano, however vast and powerful, as Etna, or



MODS II. BASALT.

some of those in the Andes, having in any anr
cient or modern eruption furnished basalt, either
in columns or in strata, it would seem an infal-
lible inference that this substance cannot be of
volcanic origin*. The wide extent also of this
substance, and the common situation of basaltic
columns on the summits of hills, strongly mili-
tate against this idea. The same formation of
basaltic columns resting sometimes on amor-
phous basalt, sometimes on indurated clay tinged
with red ochre f of iron, is found to extend near
thirty miles into Ireland from the Giants' Causy,
and as far as the northern Faroe isles, a space
of more than six degrees, or three hundred
and sixty geographical miles ; and, it is worth
remarking, nearly in the same meridian. In
like manner the basalt of Saxony might be said
by a theorist to extend through Sweden, even to
Spitzbergen; and it is observable that all the
northern parts of Europe abound with iron ;
those of Asia are concealed by perpetual ice,
snow, and marshes; while those of America

* None of the numerous hills around Etna is capped with
basalt ; nor have the isles ejected by submarine volcanoes presented
that substance; so there is no proof of a subaqueous origin. The
prisms on the shore around Etna are very rude, and unlike the
beauty and exactness of basaltic columns.

'f Does the red colour indicate heat, as yellow ochre thus as~
sumes that tinge?



I. SIDEROUS.



seem chiefly to present copper. The basaltic
columns of Germany, as is well known, are
chiefly situated on the tops of hills ; and, from
Landt's recent interesting description of the Fa-
roe isles, it appears that this phenomenon is
there equally common. A magnificent example
occurs in the isle of Osteroe.

" To the north of the village of Zellatrae there



B Fafoe f IS a ^ asa ^^ c n ^> which extends more than a
mile northwards : properly speaking, it forms
the bottom of two hills, which lie behind it,
namely Halgafieldstinden and Rodefieldstinden,
which are of considerable height, and about two
miles distant from each other. The basaltic hill
itself is about four hundred and twenty feet high,
and consists of strata of pentagonal and octa-
gonal basaltic columns, placed close to each
other in a perpendicular direction, and in such
a manner that the tops only of the farther co-
lumns are seen, while those in front exhibit their
whole form, but appear to be different in length.
These columns, which rest on a foundation of
trap about three hundred feet in height, are the
largest of the kind in the Faroe islands; for where
the rock has been freed from mould, these co-
lossal pillars may be seen with their lower ends
standing on another species of stone, and rising
to the height of above a hundred feet, all equal



MODE II. BASALT.



in size, being about six feet in diameter. Many
of these huge columns, which have fallen down,
are now lying at the bottom of the hill; one in
particular, sixty feet in length, has been thrown
across a deep gnlley, with its ends resting on
each side, so as to form a bridge over it*."

It also appears from Dr. Richardson's recent
observations f, that the basalt in the north of
Ireland occurs on the tops of hills, at a great
distance, while the intervening space has been,
as it were, scooped out by some exterior agency,
with which we are at present totally unacquaint-
ed. But whether some comet has approached
the earth, or some small planet, like one of those
recently discovered, has fallen into it, and occa-
sioned appearances altogether inexplicable upon
our small scale of observation, most probably
may ever remain a matter of theory +: and in
natural, as well as in civil history, there are
many objects of which the best judges choose to
remain in what Mr. Gibbon emphatically calls

A LEARNED IGNORANCE. Nor RlUSt it be for-

gotten, that masses of Sandstone and limestone



* Landt, 39.
f Ph. Tr. 1808.



I Dolomieu, J. dc Ph. 1791, p. 385, thinks that an exterior
shock has broken the crust of the globe, and raised parts on others.
The like ideas may be inferred from the REFOULEMENT of Saussure.



DOMAIN I. SIDEROUS.

are, in like manner, found upon the summits of
hills, quite detached from the original beds to
which they would seem to belong by the identity
of their substance. From these remarks it must
appear to every impartial mind, that the pheno-
mena of basalt are on too vast a scale, and of an
appearance too uncommon, to be produced even
by a chain of volcanoes, of which the Andes
present most extensive examples ; so that to
confine the appellation of basalt, with the French
mineralogists, exclusively to a pretended com-
pact lava, would be a mere assumption, alike
foreign to ancient erudition, and the precision of
modern science.



STRUCTURE I. AMORPHOUS BASALT*.

Egyptian. Basalt of a greyish black, with very small grains
of white quartz, and spots of iron ochre, from

Egypt!-

Basalt of a blueish grey, glimmering lustre, and

fasciculated fracture, from the same.



* It is always of a mingled aspect.

f It is only to be inferred that the Egyptian basalts do not belong
to the columnar. Ferber erroneously says, that Strabo mentions
the Ethiopic basalt as columnar. That author, lib. 17, describes a
pyramid, partly built of basalt, from the extreme mountains of
Abyssinia.



MODE II. BASALT. 25

With a mixture of amorphous black siderite,
and minute grains of white quartz, from the same.

The same interspersed with transparent felspar,
which becomes greenish from the mixture, from
the same.

Greyish black basalt, interspersed with black
siderite, partly amorphous partly crystallised, and
with greyish white felspar.

The same, with black siderite, and small grains
of yellowish green olivine.

The same, with black siderite, partly amorphous
partly crystallised, olive-green olivine, and scat-
tered particles of black mica.

The same, superficially spotted with reddish
brown, probably from the decomposition of the
iron.

Greyish black basalt, interspersed with crystal-
lised siderite, with small crystals of olivine in
square prisms, of which some being decomposed,
the surface becomes porous, while the interior is
completely dense*.

Such is the catalogue of ancient basalts observed
by Wad in the Borgian museum, there not being
even one example of basaltin, though it certainly
occurs in small Egyptian monuments; and the
author saw at Paris the statues of a king and

* Such basalts have deceived the volcanists.



S DOMAIN I. SIDEROUS.

qyeen sitting, in one piece about nine inches in
height, the back and sides being covered with
hieroglyphics. He also saw in the same collection
small fragments of green basaltin, from Egypt.

Patrin gives the following list of ancient ba-
salts*.

Oriental. " Oriental basalt of a blackish grey, of a fine
grain, mixed with white scales of felspar, and little
veins of quartz. This is the kind most commonly
observed in ancient monuments.

" Oriental black basalt. It is mixed with grains
of quartz, with small crystals of felspar, and with
spangles of mica ; these ingredients are not com-
bined as in granite, but interspersed in the black
base of trap. The Isis, which is in the court of
the Capitol, is of this stone.

" Oriental black basalt, radiated with veins of
red granite, in small grains. The two sphinxes,
which are at the foot of the great stair-case of the
Capitol, are of this basalt.

" Oriental black basalt, with green spots of si-
derite. It is called at Rome Egyptian stone, or
nephritic stone.

" Oriental green basalt. It is of the same base
as green porphyry : the only difference is, that the

* i. 127. The French authors rarely quote their authorities ; but
Patrin has borrowed his examples from Ferber's Travels in Italy



MODE II. BASALT.



substance of felspar is equally interspersed in it,
and is not united in crystals. This base is homo-
geneous, very compact, and very hard. Fine
statues of it are seen in the Capitol, and in the
Villa Albani.

" Oriental green basalt, with white specks. It is
the same as the preceding, in which the felspar is
united in small crystals : it is named speckled ba-
salt, and is very rare. There are two pillars of it
at Rome, in the church of St. Pudentiana.

" Dolomieu says, that there is such a vast
number of Egyptian monuments in the Borgian
Museum at Veletri, that they are almost sufficient
to constitute the whole Egyptian Lithology : many
are formed of stones which have qualities attri-
buted to basalts ; not one is volcanic."

In passing to the modern basalts, it must be
premised that the trap of Wallerius, which he de-
scribes as being of an impalpably fine grain,
belongs solely to the basalt of the moderns, here
called basaltin from that circumstance. But the
basaltic granite of this venerable author * certainly
includes some of the basalts of the ancients ; as
that of an iron-colour, mixed with the ore of that
metal and quartz, which is, found at Norberg, in
Westmania. His saxum ferreum, composed of

* i. 422.



DOMAIN f. SIDEROUS.



various mixtures of siderite, mica, basalt, and
quartz, may also sometimes be referred to this
Mode*.

Basalt, with mica, from Upland in Sweden.

Green basalt, with black mica, and sometimes
a mixture of quartz, from Westmania.

The basaltin of Kirwan is merely crystallised
hornblende, or siderite ; but the basaltin of Baron
de Born is often the real basalt of the ancients,
while his basalt is here called basaltin. He men-
tions that kind, mingled with green siderite and
olivine, from Bohemia; and that mingled with
brown mica, from the same country. In his
treatise on traps, Faujas confines himself to the
basaltins, or fine-grained basalts ; he mentions a
trap, sometimes black sometimes green, with grains
of semitransparent quartz, from Scotland and Pro-
vence, which may probably be classed among the
ancient basalts f. The pillars of grunstein, which
compose the innermost circle at Stonehenge, may
also belong to this division J.

* i. 437,

f Launay, Essai sur les Roches, 64, mentions a mixture of trap
and felspar, from the isle of Bornholm, Denmark.

J Townson's Tracts; whence may also be added the whin of
Salisbury Craigs, near Edinburgh, containing siderite and felspar.



MODE II. BASALT*



STRUCTURE II. COLUMNAR.



The following passage of Strabo lias been
thought to imply columnar basalt :

" We went to Philoe from^ Syene in a carriage,
through a level plain, the space of a hundred sta-
dia. Along almost all the route were to be seen,
on both sides, in many places, as it were terms* ',
of a hard, round, and polished stone, almost spheri-
cal, and of which mortars are commonly made,
placed upon a larger stone, and surmounted by
another. Some even lay apart ; the largest being
not less than twelve feet in diameter, and the
others about half as large f."

Several authors have inferred from this passage
that Strabo means to speak of columnar basalt,
but he would rather seem to imply a work of art,
a magnificent avenue from Ethiopia into Egypt.
No basaltic columns have been observed twelve
feet in diameter ; and even if the passage be cor-
rupt, and twelve feet in height be intended, or
perhaps two feet in diameter, it would still remain
so obscure, that it would be adventurous to build
any solid argument upon such an uncertain found-

* The little hermetic columns at Athens,
f Strabo, lib. 17.



DOMAIN I. SJDEROUS.



ation. It is singular that Denon, who has given
such a minute and interesting account of the isle
of Philoe, should have taken no notice of these
remarkable monuments. He speaks indeed of
large blocks of stone covered with hieroglyphics,
but mentions nothing but granite in that quarter ;
and basalt could scarcely have escaped the atten-
tion of a French traveller.

The columnar form is far more commonly as-
sumed by the basaltin, than by the real ancient ba-
salt : yet it is found even among other substances.

" Columns of porphyry are not rare; and, among
other places, are found near Dresden, several feet
in length, and not more than two inches in diame-
ter*. Columns of petrosilex compose a large
portion of a mountain near Conistone lake. Very
perfect quadrangular prisms of argillaceous schis-
tus are found near Llanurst. Rubble slate as-
sumes the columnar form at Barmouth. The
limestone near Cyfartha, in Glamorganshire, is
.divided into very regular acute rhomboidal prisms :
even the sandstone of the same district is not
unfrequently columnar; and one of the beds of
gypsum at Montmartre is distinctly divided into
pretty regular columns. Sandstone, clay, argil-

* Strange' s granitic columns, near Verona, are porphyritic, with
a paste or basis. Spallanzsmi.



MODE II. BASALT. 31

laceous iron ore, and many other substances, be-
come prismatic by torrefaction ; and the prisms of
starch formed in drying, have often been consi-
dered as illustrative of basaltic formations*."

Among the numerous examples of columnar
basaltin, it is well known that they often oc-
cur of a coarser grain, and mixed with felspar
and siderite, thus strictly belonging to the basalt
of the ancients. The columns in the north of
Italy, supposed to be volcanic, seem chiefly to
consist of this substance. I do not however find
that the German mineralogists mention their grun-
stein, as occurring in a columnar form, though
Daubuisson has evinced that grunstein and basalt
are the same substance. The analysis of Dr.
Kennedy is as follows :

BASALT. GRUNSTEIN.

Silex 46 46

Argil 16 19

Lime 9 8

Oxydofiron ... 16 17

Water and volatile matter 5 4

Soda 4 3J

Muriatic acid ... 1 1

Loss 3 1J

100 100

* Watt, Ph, Tr, 1804.



DOMAIN I. SIDEROUS.



It would indeed be a singularity that, while
basaltin occurs so often in a columnar form, a
substance composed of the same ingredients should
never assume that appearance. Yet perhaps the
columnar form of basaltin may itself be partly
owing to the impalpable fineness of the ingredients
allowing an exact scission, or crystallisation, which
coarser materials would not admit; as crystals
are generally composed of finer ingredients than
amorphous substances.

MODE III. BASALTIN.

characters. Texture finely and almost im palpably granu-
lar, sometimes vesicular ; on a large scale strati-
fied, rising like successive steps, whence the
Swedish name trap. It sometimes presents dis-
tinct Concretions, of a finer or of a coarser grain.
It seems to split in rhomboids, while the colum-
nar sometimes lapses into globular forms *.

Hardness basaltic, or between marble and fel-
spar, about 800 of the scale of Quist. Fracture
sometimes even, sometimes conchoidal. Frag-
ments amorphous j not very sharp.

Weight siderose.

* Mr. Watt, Ph. Tr. 1804, observes, that racked basalt passe*
into globules, before it assumes the compact texture.



MCHDE III. BASALTIN.



Lustre dull, except when mixed with siderite
Opake.

Colour greyish black, greenish, rarely brown
or reddish.

This is the basalt, or fine-grained trap, of the
moderns. Karsten has supposed that even the
finest basalt is a mixture of impalpable grains of
siderite and felspar, or quartz; which would in-
deed appear to be confirmed by the identity of
the chemical constituents. Faujas also argues
in favour of his volcanic theory of basalt, that
trap, which he allows not to be of a volcanic
nature, is merely a granite of a very fine grain.
This idea partly rose from the confused and lax
manner in which the term granite has been hi-
therto used ; and partly from his theory that
real basalt is always a lava. But in this way all
the mixed rocks might be classed under granites j
for there is scarcely a mixture which has not
been arranged under that head by some mi-
neralogist, as the reader may perceive from the
edition of Linnaeus by Gmelin. It is true that
a mixture of siderite felspar and quartz would
form a genuine granite, and that some of the
basalts of the ancients might be classed, as Wad
has observed, among the granitels : but where
the siderite so preponderates as to give a great
prevalence to its colour; and especially where
VOL. i. D



34 DOMAIN I. SIDEROUS,

the particles are earthy instead of being crystal-
lised, as in granite, where the silicious part super-
abounds ; a wide difference has always been al-
lowed. A variation of the same ingredients will
indeed ever form one of the chief distinctions in
mineralogy; for it must be repeated, that it is
not the ingredients, but the mode of their com-
bination, which forms the chief distinction : dia-
mond being akin to coal; sapphire only con-
sisting of clay and rust ; and, among the argil-
laceous and magnesian rocks, silex is commonly
the predominating ingredient, but still the argil
and magnesia give the character and name.

But let us listen to the great master of petra-
logy on this interesting topic.

" ^ ca ^ * ra P> a roc ^ composed of small grains
of different qualities, confusedly crystallised, in-
closed in a cement, and sometimes also united
together without any distinct cement ; and with
no perceptible regular crystals, except rarely
and accidentally.

" This definition connects traps with granites
and porphyries ; but M. Dolomieu has made it
very evident that this approximation already
exists in nature. He observed at Rome, in the
masses of granite and porphyry selected and
worked by the ancients, as we observe it in our
Alps, and in the blocks that are detached from



MODE III. BASALTW. 35

them, varied transitions between these different
kinds.

" I think besides that, in the nomenclature of
mineralogy, it must be regarded as a principle, to
Determine the kinds and species, from individuals
whose characters are the most striking ; and to
mark the transitions of doubtful and ill-defined,
substances : for the principle established in bo-
tany, of considering as belonging to the same
species, individuals between which we observe
intermediate shades, cannot be admitted in mi-
neralogy, without reducing all known fossils to
one and a single species. Indeed there is none
that may not be departed from, to make the tour
of the whole chain of those which have already
been determined, by almost insensible shades ;
and the more we shall study mineralogy, the
more this truth will become obvious, by the
number of varieties and shades that we shall
discover.

" I therefore say, that when two fossils pre-
sent remarkable differences, we must not refrain
from distinguishing them, and giving them dif-



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