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partly grey partly red, from Egypt. Wad.

Grey granite, from the same country, veined
with felspar partly grey partly red. Id.

Most of the kinds enumerated in the former
Structure may also be found in this. For the
smallest or very minute grained, see granitin.

Small grained white granite, with siderite, from
the summit of Mont Blanc.

White quartz, brown or reddish felspar, and
black siderite, from the Italian Alps.

The same, from the Isle of Elba.

Grey granite, with garnets, from Bohemia.

The same, from Norway and Scotland.

Grey granite, from Alencon. This is the com-
mon granite used at Paris.

Grey granite, with nodules of granitin, from
the Alps of Dauphiny.

Light grey granite, with red lines composed of
garnets, from Namiest in Moravia.

Grey granite, with veins of basaltin, from Nor-
way.

Secondary granite, in thin layers, from the cave
ofGribon, Isle of Mull.



MODE V. GRANITE.



STRUCTURE III. VEINED.



Saussure has described this rock with such
accuracy and precision, and has himself so distin-
guished it from gneiss, that it is surprising it
should since have been referred to the latter. In
gneiss the veins of mica run parallel through the
rock, which regularly splits in their direction. In
veined granite the seams of mica are irregular,
and terminate abruptly in various directions, being
met by the solid rock.

Saussure discusses, 1726, the differences be-
tween gneiss and his veined granite. In the latter
the elements are interlaced among each other;
while in gneiss there are fine leaves of pure mica,
which alternate with leaves composed of quartz
and felspar.

He mentions, 1799, an extent of more than
four leagues and a half of veined granite in hori-
zontal beds : and, 1802, veined granite in double
zigzag, sometimes between other beds in right
lines, which proves, according to Saussure, that it
is the effect of crystallisation. That veined in zig-
zag is of a very fine kind, the quartz being scarcely
distinguishable, while the beautiful white veins
appear to be entirely composed of granular fel-
spar, resembling a small-grained marble. The



198 DOMAIN II. SILICEOUS.

mica is also in small spangles, some black, but
chiefly of a beautiful silver white.



STRUCTURE IV. MINGLED.

Some of this kind have already been incidentally
mentioned. Besides schorl and garnets, Saussure
observed chalcedony in granite, for which see the
Composite Racks. Chlorite and actinote are not
uncommon in granite; and the talc sometimes
passes into steatite. Even calcareous spar has
been found in granite; and, when decomposed,
porcelain earth, for which see the Decomposed
Rocks. Not to mention the metals; primitive
gypsum, anthracite, gneiss, basalt, and other sub-
stances, also occur in granite.

Granite, in veins in schistus, Saussure, 599,
from Valorsine. He describes it as passing through
his roche de corne, which is generally a magnesian
basalt; the granite is of grey quartz, white fel-
spar, and grey mica, and is regarded by him as
formed by infiltration.

Granite, in veins in primitive slate, from Scot-
land.

Granite, with veins of granular quartz, from
Forez, France.

This account of one of the most important and
interesting rocks, shall be terminated by Zoega's



MODE V. GRANITE.

ideas concerning the manner in which it was sculp-
tured by the ancients, as they may perhaps afford
useful hints to the modern artist*.

" Some further observations occur concerning
the Barberini obelisk, in the engraving of which
some instruments seem to have been used, of
which there is no vestige in the large obelisks;
for the straight lines, or those which form segments
of circles, are neither sharply cut, nor have they
an equal depth ; but the concave bottom is deeper
in the middle part, and fainter at each end, till
the lines gradually vanish. Nor do they terminate
precisely in the point assumed by the sculptor;
but the slender portion extends beyond the limits
of the figure.

" Hence it is clear that the furrows were not
made with a graver, nor with emery, rubbed as
usual with a blade in the form of a knife, but
with a kind of semicircular saw, to which emery
was subjected, and by alternate motions of that
instrument. But in the right lines only ; for where
they are curved the saw must also have been of
that shape. When however the figures, which
rise in the cavities, are more turgid, and each part
disfigured with some globosity, it is probable that
they were formed with a little auger or trepan, or

* For the original, see Appendix.



200 DOMAIN II. SILICEOUS.

a kind of tube or hollow borer, by the assistance
of emery, although no vestige of sueh an instru-
ment appear, the surface of the figures having
been polished by friction. It was natural that
the artists should study to save time in this kind
of work, and effect by saws, tuctri, and friction,
what appears to have been accomplished in the
great obelisk by the chisel or graving tool, or
emery rubbed with a blade.

" 6. Our artists, when they wish to cut any
figure on granite, in the first place make a model
of a thin plate of iron, which being fastened to
the plane stone, they take another plate like a
short knife, and use it to cut a furrow, by the help
of emery, around the model first mentioned. The
furrow being thus impressed to a certain depth,
they take off the model, and begin to attack the
intermediate space with a sharp graver or chisel
called subbia. They then begin to form the figure,
with a little sharp hammer called pungetto ; and
afterwards soften it with a broader hammer called
martellino. This done, they polish it with lead
and emery ; and afterwards add the smaller linea-
ments, partly with a fine chisel, /partly with the
blade in the form of a knife and emery. Lastly,
they polish the whole with the finest emery, called
spoltrlglia.

" 7. Del Rosso thought he discovered marks



MODE VI. GRANITIN. 201

of the auger in the obelisk of Heliopolis ; and
affirms, that without this instrument characters
could not be cut in a granitic rock. But he seems
to discuss a subject which he had not studied ; for
there could be no use for the common auger, also
called a trepan, in this stone, which is harder than
iron. But the other auger, which is a brass tube
contrived to act on emery, though a convenient
instrument, is yet unnecessary, and is only used
by our artists in forming deep furrows."*



MODE VI. GRANITIN.

When granite is composed of extremely mi- Description,
mite particles, it is not easily distinguished from
basalt, or rather from basalton, the grunstein of
Werner. But where particles of siderite, or
even of basalt, which is an earthy siderite, are
mingled with particles both of quartz and felspar,
the substance is a granitin. When siderite is
mixed with felspar alone, it is basalton, or the
green-stone of Werner; the real basalt, or iron-
stone of the ancients, seeming properly to admit
of no mixture, except spangles of siderite.

Several ancient monuments, supposed to be

* Zoega de Obeliscis, p. 1 89, seq.



202 DOMAIN II. SILICEOUS.

green basalt, are really of granitin with particles
of siderite, as mica is never so much comminuted.
Granitin also often forms nodules, or veins, in
large or small grained granite, in almost every
country where that substance occurs ; but this
substance being rather of microscopic observa-
Green basalt, tion, the specimens are not common. Green
basalt, properly so called, should be homoge-
neous, or present only spangles of siderite ; but
may contain occasionally very minute particles
of quartz only. The Isis of the Capitol, Ferber,
231, is of granitin.



MODE VII. GRANITON.

When the crystals, especially those of felspar,
are extremely large, that is, from two to six
inches or more in length, the substance may
well be called a graniton. It is common in the
Alps, and other granitic mountains; and exam-
ples may be seen in the foot pavement of West-
minster bridge*. Graniton presents the com-
mon colours of granite, that is, white, grey, and
red.



* Mr. Smeaton says it came from Llanlivery, near Fovvey, in
Cornwall.



MODE VIII. GRANITEL. 203

Graniton may also be denominated, from the
mica assuming the size of plates of talc.

Other aggregates, often confounded with gra-
nites, may be found in the division of Composite
Rocks.



MODE VIII. GRANITEL.

The mountains called primitive chiefly con- Definitions,
sist of four substances, blended in various mix-
tures, namely, felspar, quartz, siderite, and mica,
Without three of these substances the appel-
lations of granite become vague and improper 5
and have occasioned great confusion in orology,
or the description of mountains. Where only
two occur, the greatest of all geologists, Saus-
sure, has used the name gramtel ; and his ap-
pellations, when not contradicted by necessary
distinctions arising from recent discovery, ought
always to be received with singular respect.
The term granitel is also confirmed and appro-
priated by the circumstance, that as the word
granite is now consecrated by universal and
perpetual usage, being derived from the Italian
granito, as presenting the appearance of grains
or kernels *; so a modification of granite ought,

* It has been ridiculously said, that it is derived from the ge-
r unites of Pliny ; which would only imply a stone shaped like a



204 DOMAIN II. SILICEOUS.

in due analogy, to receive its name from the
same language.

Granitel sometimes consists of as minute par-
ticles as granitin, so as to assume the appearance
of a coarse basalt. From this confusion, as
Wad observes, some of the Italians denote the
same substance granitello verde di Egitto, which
others call basalte verde. He describes two spe-
.,.,-.;. cimens*: " 1. Granite with very minute grains,

consisting of greyish white felspar, and siderite
of a dark green, in equal portions. 2. Granite
of a very small grain, composed of greyish white
felspar, and greyish black siderite, mixed with a
larger portion of olive-green siderite, which ren-
ders the rock green."

Mr. Kirwan has justly observed, that the sim-
ple addition of mica to any stone, cannot alone
entitle it to be placed in the granitic division, as
mica does not form a grain, but attaches itself
indifferently to many sorts of stones ; for there
are micaceous limestones, micaceous sandstones,
micaceous serpentines, &c. &c. Mica must
therefore be totally excluded from the granitels;
and felspar with mica, or quartz with mica, can

crane's bill, geranium! But Pliny says himself, xxxvii. 1 1, a gruis
collo geranites. See Laet, p. 170, for a print of a Geranites. For
the first appearance of the word granito, see a former note.
* Fossil .ZEgyp. p. 7



MODE VIII. GRANITEL. 205

only be properly classed with the simple rocks
of felspar or of quartz. There are therefore only
three genuine structures of granitel; namely,
1. Felspar with siderite. 2. Felspar and quartz.
3. Quartz with siderite.



STRUCTURE I. WERNERITE, FELSPAR WITH SIDERITE.

The appellation has been derived from this Wemerite.
celebrated mineralogist, who well deserves to give
his name to one of the most important substances
in nature. It is also intended to compensate,
while it calls to memory, his noted syenite, a term
so ill chosen as to have introduced confusion, in-
stead of illustration. The syenite of Werner, as
already mentioned, consists of felspar with side-
rite, that is, the former is more abundant; but
in basalton, or grunstein, the siderite predomi-
nates, and gives a black or greenish colour ; while
Wernerite is generally reddish. Yet the syenite
of Werner sometimes contains quartz and' black
mica, which infallibly constitute a granite; and
the stone should, in that case, be said to pass into
granite. The appellation of Wernerite is here
strictly confined to a mere and sole admixture of
felspar with a smaller portion of siderite ; and as
colours form the meanest of all distinctions, no
consideration is paid to that circumstance.



DOMAIN II. SILICEOUS.



Wemerite of white felspar and black siderite,
from Mount Sinai. It sometimes passes into
granite; and is reported by tradition to be the
stone on which the commandments were en-
graven.

Of red felspar and black siderite, from the
Alps. It is sometimes mixed with mica, or schorl;
and if quartz were present, it would then consti-
tute a granite.

Of grey felspar and black siderite, from the
ejections of Vesuvius. These substances united,
or distinct, may be said to form all the lavas. It
is sometimes mixed with garnets or actinote.

Wernerite of grey felspar with black horn-
blende, forming a vein in granite, on the summit
of Mont Blanc. Saussure, 1987.

Wernerite, from Muhr in Stiria.

Wernerite, in rolled pebbles, from the Lake of
Geneva.

Of brownish red felspar and black siderite,
from Leipzig.

Of reddish white felspar and black siderite,
from the Hartz.



STRUCTURE II. LEHMANITE, FELSPAR WITH QUARTZ.

Lehmanite. This name is given to a primitive substance,
from the celebrated Lehman, who first pointed



MODE VIII. GRANITEL. 207

out the distinction between primitive and second-
ary mountains.

Lehmanite of felspar and quartz, from Corn-
wall.

The same of white quartz and red felspar, from
Scotland.

It is common in the Alps, and other chains of
mountains.

Lehmanite of a reddish white, from Sweden*.

Lehmanite, from Grimsel. It is also found in
Nassau and Siberia, and near Portsoy, in Scot-
land. Linnaeus, by Gmelin, 214.

Of a yellowish white, from Finland.

Da Costa says, p. 278, that part of Newry,
Ireland, is built of this stone, there called mountain
grit. Another part is of felspar and large green
mica.



STRUCTURE HI. HENKELITE, QUARTZ WITH SIDERITE.

The name is derived from Henkel, who may be
ranked among the fathers of lithology. The al-
liances between quartz and siderite seem to be
rather uncommon, felspar having been commonly
mistaken for the former substance.

Henkelite, from Switzerland.

* Wall. i. 422.



208 DOMAIN II. SILICEOUS.

In Switzerland it often contains garnets.

The same, from Altenberg, in Saxony*.

The basaltic granite of Wallerius, from Suder-
mania. It is either black, yellowish, or greenish.

The same, of an iron colour, from Norberg, in
Sweden; but this seems rather to belong to the
siderous division.

Henkelite is also found in Bohemia, Saxony,
Tyrol, Stiria, &c. It is believed that the ancient
black and green granites, so called, often consist
of this substance f.

STRUCTURE IV. MINGLED.

The most usual parasitic stones of granitel are
schorl and garnets, both composed in a great part
of iron.

Wernerite, with garnets, from Vesuvius.

The same, with actinote, from the same.

Lehmanite, with steatite, from the Alps.

Henkelite, with garnets, from the Alps.

The same, with steatite, from the same.

The same, with schorl, from the same.

* Linn. 218.

t Launay, Essai sur 1'histoire naturelle des Roches, Bruxelles
1786, 12mo. p. 41.



DOMAIN II. SILICEOUS. 209



MODE IX. GRANITOID.

Many rocks, inaccurately classed among gra-
nites, are reserved for the Composite Domain.
Such alone as perfectly resemble granite, but
are of a very different modification, are here
styled granitoids; and this denomination pre-
sents three different structures.

STRUCTURE I. CALCAREOUS GRANITE.

In this rock lime-stone supplies the place of fel-
spar. This substance was first mentioned by
Kalm, as forming chains of mountains in Canada.
It was afterwards described by Saussure. Wer-
ner told me that he regarded it as a truly primi-
tive lime-stone,

Calcareous granite, from the mountains of Ca-
nada.

The same, from the vicinity of Mount Cenis.
But in the Alps it more commonly assumes the
form of gneiss, as at Roth Horn, Mont Cervin, &c.

Reddish calcareous granite, or primitive lime-
stone with quartz and mica, from Scotland*.

* The Journ. de Ph. 17Q1, mentions a calcareous granitoid, the
lime-stone or spar being in globules of an oval form, with crystallised
facetts, and compressed horizontally.

VOL. T. P



DOMAIN If. SILICEOUS.



STRUCTURE II. ARGILLACEOUS.

This rock is more often the product of decom-
position, which changes the felspar into clay.

Argillaceous granite, with quartz, mica, and
martial clay, from Hungary and Sweden.



STRUCTURE III. TALCOUS.



From this division talc, and even steatite, must
be excluded, as being often mere modifications or
decompositions of mica.

Granitoid of felspar, quartz, and serpentine,
from Transylvania.



MODE X. GRANITIC PORPHYEOID.

Description. In this substance, which is very frequent in
nature, some large or distinct crystals of felspar
are sprinkled on a base of granitin; and the
base being here assumed as the only ground of
classification of the substances vaguely called
porphyries, it must of course fall into this divi-
sion. The base may consist of quartz, felspar,
and siderite; or quartz, felspar, and mica; or
even any two of these substances, Some of the



MODE XI. GNEISS.

porphyries of Saussure, 150, belong to this
class ; but granitic porphyroids are so abundant
in all primitive mountains, that it is scarcely
necessary to select examples, being a mere va-
riation in the construction of granite or granitin.

Granitic porphyroid, from Mount Cenis.

The same, from Cornwall, Wales., Scotland,
the Vosges mountains in France, the Alps,
&c. &c.

Saussure, 155, gives some curious observa-
tions on the transitions from granite to granitic
porphyry. A great portion of Forez is of por-
phyry; while the adjacent portion of Auvergne
is granitic.



MODE XI. GNEISS.

When the materials of granite are disposed in Distinction*
thin layers, or plates, the substance assumes the
name of Gneiss ; which consequently consists of
quartz, felspar, and mica. In his two first vo-
lumes, published before Werner had introduced
greater precision into the science, Saussure has
sometimes used the term veined granite, to ex-
press what is now denominated gneiss. But in
his latter volumes, as already explained, his
veined granite differs from gneiss, as presenting



DOMAIN II. SILICEOUS.



only short and irregular veins, terminating iff
solid masses; while in gneiss the veins are uni-
form, and regularly divide the whole, as in slate,
or in other substances properly schistose. Hence
gneiss has also been called schistose granite by
the French, and other writers.

In gneiss the mica is generally more abund-
ant, as dividing the substance into regular plates.
Sometimes the place of mica is supplied by
siderite, which, as already explained with regard
to granite, cannot be regarded as altering the
denomination, but is only a proof of greater an-
tiquity. The siderite is also sometimes inter-
spersed in thick layers, or even beds. One of
the most interesting kinds of gneiss, is that with
Red. red felspar, sometimes of a wavy or undulated
structure, and which is also considered by some
as the most ancien . This, like other schistose
contorted, substances, is found contorted, or convoluted, in
fantastic forms; by some regarded as originating
from internal expansion or disturbance; while
others consider it as the mere effect of a parti-
cular crystallisation.

Primary. Geologists in general have considered granite
as the oldest substance, the fundamental rock
which supports all the others: the Huttonians
however regarding it, on the contrary, as the
newest substance, which, being elevated by ex-



MODE xi. GNEISS;

pansion, has broken the other stratifications.
However this be, it is certain that gneiss has, in
the grand example of the Alps, been found un-
der granite confessedly primitive; and they are
often found alternating with each other. The
lofty mountain of Rosa, which only yields in
height to Mont Blanc, instead of being com-
posed of arrects or uprights*, that is vertical
layers, or plates like the latter, presents, on
the contrary, horizontal beds of veined granite,
gneiss, and other schistose substances f.

Intermixed with gneiss are sometimes three
principal rocks, all regarded as primitive; lime-
stone, siderite either solid or schistose, and por-
phyry. But these substances equally appear
intermixed with granite, only alternating verti-
cally; while in gneiss they present horizontal
beds. In the old Egyptian monuments nothing
is more common than to find large masses of
siderite intermixed with the granite; and even
basaltin often penetrates that substance. The
Egyptian monuments of mica slate, described
by Wad, may perhaps more properly belong to
gneiss.

* In a new science new words must be admitted. Saussure,
and others, have long lamented the absurdity of vertical itds w
layers. Arrects t>r uprights would supply the deficiency.

f Sauss. 2138.



DOMAIN II. SILICBOVS.

Primitive lime-stone likewise alternates with
granite, and has even been found to assume the
granitic forms. The alternation of porphyry
with granite is of general observation in all pri-
mitive mountains.

Gneiss also frequently contains garnets, acti-
note, magnetic iron, and pyrites. It is, after
clay-slate, the most metalliferous of all rocks.
The chief mines of Saxony, Bohemia, and Salz-
burg, are situate in this rock, which, though
very common on the Continent, is comparatively
rare in Great Britain and Ireland.



STRUCTURE I. TABULAR, OR IN THICK SCHISTOSE
FORMS.

This kind is commonly derived from granite, or
passes into that rock.

Tabular gneiss, from the Alps.

The same, from the isle of Leuis, in the exte-
rior chain of the Hebudes, Scotland.

STRUCTURE II. LAMINAR.

This is the common appearance of gneiss, and
may be divided into two Aspects.

Aspect 1. Plane or level. Gneiss, with red
felspar, from the Alps, Norway, Saxony.



MODE XI. GNEISS. 215

Gneiss, with white felspar, from the same coun-
tries, Salzburg, Greece, &c. It is a common, and
seems a fundamental rock in the Brasils. Mr.
Jameson says, that it is found in the isles of Coll,
Tirey, and Rona; also in the Shetland isles, and
many parts of the main land of Scotland.

Aspect 2. Undulated. This is more uncommon
than the former.

Undulated red gneiss, from the Alps of Dau-
phin y.

The same, singularly contorted, from the same
site. This forms a remarkable diversity.

Red gneiss, from Norway.

Grey undulated gneiss, from the same countries.

STRUCTURE III. IRREGULAR.

In this kind the layers intersect each other irre-
gularly, in the form of wedges, &c. It differs
from the veined granite of Saussure, because the
divisions do not terminate in massy portions, but
are continued in oblique and irregular directions.

Red irregular gneiss, from the Alps, Norway,
&c.

Grey, from Brasil, and other countries.



DOMAIN II. SILICEOUS,



STRUCTURE IV. COMPOSED OF TWO SUBSTANCES.

Interesting examples of this kind occur at the
mines of Salzburg, and particularly at those of
Macugnaga, near Mount Rosa, in the north of
Italy. This rock has always been called gneiss,
but is composed of thickish plates of quartz, with
thin seams of foliated mica, or rather steatite.
Gneiss also occurs composed only of felspar and
mica. As the first of these kinds has been chiefly
observed in Italy, I would propose to call it
Pi n i te > fr m Pi m > an illustrious geologist, who
explored the southern Alps. The other may be
called Ferberite, an honour due to Ferber, whose
travels illustrate many parts of Italy, and the
south of Germany,

Aspect 1. Finite of quartz and steatite, from
Macugnaga, near Mount Rosa.
The same, from Salzburg.

Aspect 2. Ferberite, from the Alps, &c.
Gneiss also occurs of quartz and siderite, and
pf felspar and siderite.



MODE XI. GNEISS. 2 17



STRUCTURE V. MINGLED.

Grey gneiss, with garnets, from Bohemia,

The same, with actinote, from the same.

The same, with pyrites, from Bohemia.

The same, with different metals, from various
countries.

Finite, with gold pyrites and native gold, from
Macugnaga.

The same, with native gold, from Salzburg.

The following examples of various kinds may
be added, from Saussure :

A remarkable gneiss, of a bluish grey mica, in-
closing long grains of quartz and felspar, which
appear like sand, but are in fact crystals more or
less regular. 1221.

A gneiss, composed of irregular layers of white
granular quartz, and leaves of a substance inter-
mediate between slate and steatite. 2044.

A fine gneiss, composed of black mica, ap-
proaching in splendour to graphite, intermixed
with particles of felspar, and sprinkled with small
garnets. 1732.



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