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regarded as a kind of tripoli, but is neither porous
nor of a slaty structure. He concludes that tri-
poli consists of a fine sand of felsite.



MODE V. GRANITE.

This important substance, which composes Composition,
the highest chains of mountains, and was used
by the Egyptians in the earliest monuments of
art, is chiefly composed of felspar and quartz,
which have been already described : a third sub-
stance is also indispensable in granite, namely,
either mica or siderite. And even when both
these latter are joined, the most exact mineral-
ogist or geologist could not refuse the strict ap-
pellation of granite, as different mixtures may
be found in no very remote parts of the same
rock. As some granites, instead of felspar, pre-
sent felsite, yet are universally admitted into this
class ; so the mica may pass into talc or steatite,
or siderite, as on the summit of Mont Blanc, and

VOL. i. N



DOMAIN II. SILICEOUS.



the siderite into iron, without changing denomi-
nations. Crystals of schorl, or garnets, not to
mention the preciotis stones, may also appear in
genuine granite; but the real and severe deno-
mination can in no case be further extended.
When there are only two essential substances,
with a granitic appearance, as particularly
Granitei. quartz and felspar, the term granitel must be
admitted, with Saussure, Kirwan, and other ce-
lebrated geologists; though in Italy gramtello
is used by artisans for a complete granite, com-
posed of very small grains, here called granitin;
as basaltin is a fine basalt, and porphyrin a fine
porphyry.

These observations become the more neces-
sary, as no substance has engaged more attention
in systems of geology, and no two authors seem
hitherto to be agreed in precise and formal
definitions of granitic substances: and in all
sciences it is well known that no question can
be settled, or even accurately discussed, without
the most precise definitions. Thus in the ques-
tion concerning the entrance of granitic veins
into primitive schisti, some deny that the granite
in these veins is of the same mixture with the
mass; and it certainly would considerably in-
fluence the discussion, if the mass be a complete
granite, and the veins only granitel. Nor in



MODE V. GRANITE.

fact can there be any just science, if terms be
used in a lax acceptation; and it is far better
to err in the contrary extreme, which can only
be accomplished by increasing the number of
distinctions and denominations, as has been done
in gemmology.

As siderite has been shown to be among the Granite, with

sidente.

most primeval substances, and is found enclosed
in the crystallisation of the most ancient gra-
nites, so as to evince a priority of formation to
the quartz, or the felspar, which never appear
to be intercepted by the siderite; so it may be
assumed that a granite, consisting of felspar,
quartz, and siderite, with or without the addition
of mica, may be regarded as among the most
ancient, if not absolutely primary. Saussure
observes that there is no mica in the granite on
the summit of Mont Blanc, its place being sup-
plied by siderite ; and remarking the same dif-
ference to occur in the granite ejected from the
depths of the Italian volcanoes, he is led to the
reasonable conclusion, that this construction,
being found at the greatest heights and the
greatest depths, must be the most primordial.
It is also remarkable, that as the nucleus of the
earth is inferred by astronomers and natural phi-
losophers to consist of iron, which is seldom
found free from silex, so a great part of the sum-



DOMAIN II. SILICEOUS.

mit of Mont Blanc consists of granitel*, or a
mixture of felspar and siderite ; and the base of
all lavas consists of one of these two substances.
Whether however we join the Huttonians, in
considering granite as the newest substance, the
last ejected from the bowels of the earth; or the
Wernerians, in regarding it as the most ancient,
being deposited from above, we must be allowed
to view a substance composed of felspar, quartz,
and siderite, as not only a complete and genuine
granite, but as perhaps the most noble denomi-
nation of that class.

As Mont Blanc is the most remarkable gra-
nitic mountain in the world, it maybe instructive
to translate Saussure's curious and interesting
account of its summit. Of the rocks which that
great observer discovered near the summit of that
mountain, he gives the following description ;
which shall be followed by that of the rocks
observed on the summit itselff.

* This, as Saussure especially mentions, 10)94, was the syenite
of Werner at the time when he wrote, A. D. 17Q5; but Karsten
about the same period defined the syenite of Werner to consist of
quartz, siderite, and felspar. Jameson however regards syenite as
composed of felspar and hornblende; but Kirwan agrees with
Karsten. Daubuisson, who is commonly exact, says that syenite is
composed of felspar and siderite; and that any quartz or mica is
accidental.

f Saussure, 1Q9Q, supposes that the summit of Mont Blanc
was originally about two leagues under the surface of the earth.



MODE V. GRANITE.



1987. " The naked rocks that we there meet
with, and which form two kinds of arretea or
crests, of a black colour, and somewhat saliant,
which we clearly see from the banks of our lake
to the left of the highest summit of Mont Blanc,
are granites, here detached in scattered frag-
ments ; there, in solid rocks, divided by fissures
nearly vertical, whose direction is conformable to
that which generally predominates in these moun-
tains, that is, from the north-east to the south-
west, and which I consequently regard as layers.

" The felspar which enters into the compo-
sition of these rocks is white approaching to
grey, or green, or redish ; it yields under the
blow-pipe a glass, from which we may obtain
globules of 0,6, transparent, colourless, but full
of bubbles.

" The felspar is here pure, there covered or
even mixed with a substance of a grey, inclining
to a sea-green, colour; without lustre, earthy,
soft; when scratched, whitish grey. This sub-
stance appears to be an earthy steatite; it is
difficult to obtain pieces of it free from felspar ;
those that I separated, melted under the blow-
pipe into a greenish glass, translucent, and of a
very unctuous aspect. They became discoloured
on the iron rod, and dissolved with effervescence.

ce The whitish, semi-transparent quartz, which



DOMAIN II. SILICEOUS.



enters into the composition of this granite, ap-
pears a little unctuous in its fracture; a frag-
ment, of the fifteenth of a line long by a thirtieth
in thickness, or of 0,06? by 0,033, fixed at the
extremity of a thin rod of iron, became perfectly
rounded in the flame of the blow-pipe, losing a
little of its transparency, which in this piece
appeared perfect, and some bubbles rose in its
interior. This quartz is therefore more fusible
than rock crystal, in the proportion of 0,035 to
0,014.

" These granites are frequently mingled with
hornblende, here blackish, there inclining to
green.

" There is also seen chlorite, often of a black-
ish green, sometimes in veins, sometimes in nests,
and even in pretty thick masses. It is soft, but
not friable ; of a very fine grain, and its small
particles, viewed by the microscope, appear very
translucent thin plates, of a bright green; but
they have not the regularity of those of St.
Gothard, which I have described in 1893.
This fossil, like hornblende, appears to retain in
these granites the place of mica, which does not
appear in it, except in very small and scarce
spangles.

" Some of these granites appear curious, there
being small cavities of angular and irregular



MODE V. GKANITE.



forms, full of a rust, or brown dust. In breaking
these granites, we find in their interior small
pyrites, brown and dull on the outside, but bril-
liant and of a very pale yellow within, and whose
fragments are attracted by the magnet. It is
from the decomposition of these pyrites, that the
cavities arise. Aly guides found fragments of
these granites, wherein were cubical pyrites from
three to four lines in thickness, whose fracture
is very brilliant, and of a very lively brassy yel-
low : these do not decompose in the air.

" We also find in these rocks quartz, with
veins and nests of delphinite, or green schorl of
Dauphiny (actinote) ; it is but confusedly crys-
tallised, but easily known by its puffing up un-
der the blow-pipe, and by the black and refrac-
tory scoria into which it is changed.

" In some parts these granites degenerate into
irregularly schistose rocks, composed of quartz
and felspar, without any mixture of mica, and
whose layers are separated and covered with
an argillaceous, nut-brown, ferruginous earth,
which melts into a black glass.

" These same rocks of granite contain a vein
of granitel almost entirely composed of laminar
black and brilliant hornblende, and of grey
translucent felspar, which assumes outwardly a
rusty colour.



184 DOMAIN II. SILICEOUS.

<c In short, my guides found also in these
same rocks a palaiopefre, or primitive petrosilex,
of a grey approaching a little to green, trans-
lucent at the thickness of a line, and even to
1, 2, scaly in its fracture, hard, interspersed in-
ternally with dots of a deep green, which are
scarcely visible but with a magnifying glass, and
which appear to be steatite ; and also some rare
dots of pyrites, which, in decomposing, stain of
a rusty colour the vicinity of the places they
occupy. This stone melts under the blow-pipe
into a white and bubbly glass, like that of the
felspar."

Our intelligent author thus describes the rocks
he observed on the summit itself of this cele-
brated mountain :

1990. " These rocks, situated nearly 240Q
fathoms above the sea, are interesting by their
being the most elevated of our globe that have
been observed by naturalists. M. Bouguer and
de la Condamine ascended the Andes of Quito
to an equal height, and even some fathoms
higher than that of these rocks (2470 fathoms) :
they were not however acquainted with rocks;
but as they are said to have sent to France
chests full of specimens of the mountains, on
which their trigonometric operations had con-
ducted them, I could have much wished that



MODE V. GRANITE. 185

these specimens were examined by connoisseurs.
The late duke of Rochefoucault, a man equally
distinguished by his knowledge as by his virtues,
and who fell the innocent victim of the troubles
of a country for which he had made, and would
have yet made, the greatest sacrifices, was very
willing, at my entreaty, to make the most careful
researches after these specimens, either at the
King's garden, or at the Academy of Sciences,
of which he was a member ; but he was neither
able to discover them, nor any trace of what had
become of them.

" The scarcity of specimens of rocks situated
in similar heights, and the inferences we might
draw from their nature in different systems of
geology, induces me to give a detailed descrip-
tion of these.

(C They are like those of 1987? granites in
mass, where hornblende and steatite hold the
place of mica, which is there extremely thinly
scattered ; the sun and a magnifying glass are
necessary to enable us to perceive some white
and brilliant spangles; it is even doubtful if
these brilliant particles, which it is impossible to
detach, are really mica.

" Felspar forms the dominant part of these
granites; constituting about three fourths of
their mass. Their crystals, nearly parallelopi-



186 DOMAIN II. SILICEOUS.

peds, vary as to size ; there are some which are
an inch long, by six lines broad. They are of
a dull white, slightly translucent, little brilliant,
of the kind I have called dry ; under the blow-
pipe they yield a transparent glass, but with
bubbles, from which may be formed globules of
0,81, and consequently fusible at the ?0th de-
gree of Wedgewood. Upon the rod of sappare
the bubbles dissipate, and there remains a trans-
parent milky glass, which sinks without pene-
trating or dissolving. These crystals of felspar
appear here and there greenish and dull, on
account of a slight coat of earthy steatite which
covers them.

" The quartz, which forms a little less than
the fourth of the mass, is of a grey approaching
to violet colour; its fracture is uneven, brilliant
in some places, not scaly, but here and there
rather conchoidal, a little flat. Its fusibility is
nearly the same as that of the quartz of the gra-
nites of 1987.

" The hornblende, which forms in the mass
too small a portion to be estimated, is of a black
approaching to green ; it shows some tendency
to the laminar and brilliant form ; but it is more
often merely glimmering, and almost earthy;
fusible into a brilliant black glass, but porous in
its interior ; and which on the rod of sappare



MODE V. GRANITE.



passes to the bottle green, through the brown;
afterwards loses its colour, and dissolves with
some effervescence, which proves there is a mix-
ture of magnesian earth.

" The earthy steatite, which also forms a very
inconsiderable part of the mass of these granites,
resembles that of 198?.

" All these granites have their natural divi-
sions covered with some coat, either green or
blackish. This is an earth like chlorite, of a
green almost black, and a little shining on its
external surface, but of a more bright green and
earthy in its fracture; soft, scratching with a
greenish grey streak; at first turning brown un-
d- r the blow-pipe, then yielding a knob = 0,3,
or fusible at the 189th degree of Wedgewood.
This knob has a metallic aspect, somewhat un-
equal, and a little dull, like that of bars of melted
iron; and not only the knob, but all the parts
that the action of the flame renders brown, are
strongly attractable by the magnet. A small
fragment tried upon the rod of sappare, at first
infiltrates like ink between its fibres, then be-
comes of a dull brown, and at length entirely
discolours, but without any appearance of dis-
solution.

: The green coat which covers other pieces
of these granites in their spontaneous divisions,



188 DOMAIN II. SILICEOUS.

is less dark, pretty shining, translucent, smooth
and even a little unctuous to the touch, soft,
easily scratched to grey, changing under the
blow-pipe into a translucent glass, which be-
comes transparent on the rod of sappare and
dissolves, but without effervescence. This coat
appears to be of the nature of steatite; but I
have not been able to obtain pieces of it suf-
ficiently large to measure its degree of fusibility."

The rocks of the southern parts of this sum-
mit he thus describes, 1993 :

" 1. Granites perfectly similar to those before
mentioned, 1987.

<e Q. Syenites or granitels, that is, rocks com-
posed of laminae of black hornblende and white
felspar, also laminar, but both in such small
parts, that we may as well give the name of
trap to these rocks, according to the definition
I have given in 1945.

" 3. A primitive petrosilex, or pala'iopetre, of
a pearl grey, translucent to two thirds of a line,
with a scaly fracture in large and small scales,
sufficiently hard to yield bright sparks, but hav-
ing a grey streak when scratched by a sharp-
pointed steel. Under the blow-pipe we may
form globules of 0,45; which indicates the
fusibility of pig-iron, 126 or 130 of Wedge-
wood. It is a grey glass, semi- transparent.



MODE V. GRANITE 189

bubbly, which on the rod of sappare gains in
transparence and sinks, but without penetrating
or dissolving, and even without entirely losing
its bubbles.

" This palaiopetre contains veins of from one
to three lines in breadth, which cross at different
angles, and small nests of a deep leek-green horn-
blende, confusedly crystallised, or in plates rarely
straight, or in middling large fibres."

STRUCTURE I. OF A LARGE GRAIN.

Aspect 1. Felspar, quartz, and siderite, often
joined with mica.

Red granite of Egypt, from the quarries visited
by many travellers beyond Syene, whence it is
called Syenites, by Pliny, who specially mentions Syenites,
that the obelisks are composed of it ; while it is
universally admitted that they are a mere and ge-
nuine granite, often containing no siderite *.

* Both Agricola and Aldrovandi mention syenite : the latter
says, Fulgus qppellat hoc genus marmoris granitum rubrum cum
antea diceretur pyrrhopoikilon ; the latter word being also used by
Pliny to denote the fiery red variegation of the felspar.

The celebrated Zoega also informs us positively that all the obe-
lisks are of the ancient Syenite, that is, as he adds, our red granite.
" Verum enimvero omnes obelisci in Europae civitatibus obvii,
ubi excipias unum Florentinum (e granite fusco), et maxima quo-
que pars eorum qui in ^Egypto exstant, atque in Abyssinia ; facti



DOMAIN TI. SILICEOUS.

The. learned M. de Sacy, in his recent trans-
lation of Abd-allatif, or Abdolatiph*, who, about
A. D. 1210, wrote a curious account of Egypt,
uses the words die, est de granit, de cette pierre
rouge, tiquetee, qui est d'une extreme durete.

It appears from the same work that some of
the pyramids were covered with granite, and even
with hieroglyphics ; which the Arabian author says
might fill a book of ten thousand pages. Gro-
bert, in his description of the pyramids, mentions
the fragments of that covering, as granite of rose-
coloured felspar, a little quartz, and black siderite,
like that of Elephantina, near Syene. This cover-
ing existed till at least the thirteenth century.
Curious authorities concerning the granitic column
called Pompey's, particularly that of Apthonius,

sunte Syenite lapide, quern et pyrrhopcecilum vocat Plinius ; I tali
autem granito rosso, lithologi graniten rubrum." Zoega de Obeliscis
Roma? 1707, folio, p. 140.

Petrini, on breaking some pieces, found that when there was
hornblende, it was always mixed with mica; as it is in the large
black spots. Ibid.

Granite seems first to be mentioned by a writer of the middle
ages, Vacca, whose description of Rome is published by Mont-
faucon in his Diarium Italicum. Vacca repeatedly mentions mar-
mor granitum JEthalioe insulce, that is, " granite marble from the
isle of Elba," whence he supposed it came. The \vord granito is
probably as ancient as the restoration of the arts in Italy, in the
thirteenth century.

* Paris, 1810, 4to. p. 182.



MODE V. GRANITE



A. D. 400, may be found in the same work. It
belonged to the Serapeum, which was a noble
library, much reduced by Diocletian, when he
ordered the Egyptian works of alchemy to the
flames*.

The same, with large patches of siderite, in the
sphinxes of the museum at Paris.

The same, running in veins through grey gra-
nite.

Grey granite of Egypt, consisting of felspar,
quartz, and siderite : the psaronion of the ancients,
from its resembling the colours of a starling.

Black and white granite, consisting chiefly of
siderite with quartz, and a little felspar.

Dull green granite, of green siderite, with a
little quartz and felspar.

Yellowish granite, of granular quartz, yellowish
felspar, and greenish siderite, in large plates with
metallic lustre, from Zillerthal.

Red granite, of felspar, quartz, and hornblende,
from Peterhoffin Russia.

The same, from Mount Sorel in Leicestershire.

* Oros. vi. 15. Some theoretic French writers had inferred that
the Egyptians were negroes (in opposition to the mummies them-
selves), because they thought the Sphinx has negro features. Abd-
allatif, p. 179, tells us it was originally painted red, and the colour
was still fresh in his time ; nay Grobert, p. 32, observed a yellowish
tinge in parts not rubbed.






192



DOMAIN II. SILICEOUS.



It also appears in masses on the road to Quarn-
don.

It is also found in Greece, Norway, Saxony,
the Hartz, Suabia, Stiria, Scotland, and many
other countries.

Aspect 2. Felspar, quartz, and mica. Red
granite of Egypt, without siderite, which, as Wad
justly observes, constituting all the obelisks, is the
real Syenites of Pliny. The mica is sometimes
greenish black, sometimes tombac brown, some-
times grey, sometimes black.

The same, variegated with grey felspar.

Grey granite, psar onion, of the same compo-
sition, from the same country.

Green granite. Of this I have only seen one
specimen, found by Roziere in the ruins of Om-
bos, in Upper Egypt. It is the most beautiful of
all the granites, the felspar being of the finest
emerald green, the mica silvery, and the quartz
transparent white*.

Blue granite, of white quartz, silvery mica, and
felsite of a sky blue, from Krieglach, in Stiria.
This granite, which is found in large masses in the
highway, only yields in beauty to the green of

* Besson, in his memoir on the granitel of Corsica (/. de P/*.),
mentions a granite of greyish quartz, and beautiful semi-transparent
green felspar.



MODE V. GRANITE.



193



Egypt. Born says, that even the quartz is some-
times tinged with blue ; which may be the Prus-
siat of iron.

Red granite, with large mica, approaching to
talc, from Portsoy, Scotland.

The same, with crystals of schorl, from the
same place.

Red granite, joined with Tirey marble, from
the Isle of Tirey.

Rose-coloured granite, from the Lago Mag-
giore.

Brown, or Isabella colour, from the Vosges
mountains, France. .

For the green of the Vosges, see Talcous rocks.

White granite, from the Alps, which are chiefly
composed of this substance.

Reddish granite, from the Carpathian moun-
tains. Born, i. 377.

Red granite, in which the felspar assumes a
round or oval form. This granite, found not far
from Petersburg, forms the basis of the statue of
Peter the Great. Patrin, i. 95*.

Pale yellow granite, from Greenland.

Granite, with pearl-coloured felspar, from
Austria.

Granite, with red felspar, and very long-grained

* Pini (Felspatbs de Baveno, 1779, 8vo - P- 41) mentions oval
crystals of felspar, like a cylinder on an oval base.
VOL. I. O



DOMAIN II. SILICEOUS.

mica, which passes into siderite, from the cele-
brated quarry near Petersburg. Karsten Lesk.
Mus. 374.

. Granite, with milk-white felspar, spotted with
red, from the same place. Ib.

Granite, with tombac brown mica, from Bo-
hemia.

Granite, with Labrador felspar, from Norway.

White granite, of which the Escurial was built,
from Spain.

Violet granite, containing large crystals of vio-
let-coloured felspar, from the Isle of Elba.

Grey granite, from the Hartz.

White granite, from the Cevennes mountains.

Dark blue granite, from Brazil.

Black granite, with black felspar, from the Alps.

Grey granite, from Cornwall, the moorstone of
the country. It is white, with black and white
mica, large-grained, and takes a good polish. Da
Costa, whose book appeared 1757, says, p. 273,
that it abounds with that kind of quartz which is
called jfefcjDdT by the Germans. In the infancy of
the science the names of discrimination were very
few ; and they will increase in proportion as it
advances*.

* In his Observations Miner alogiques sur les Vosges, Nancy,
1782, 8vo. Sivry informs us, p. 93, that, on a mountain near Giro-
magny, there occur varieties of beautiful granites in detached blocks ;



MODE V. GRANITE.

The granites near the Hermitage, in Dau-
phiny, which yields the famous wine so called,
often present specks of a greenish black mica in
the very heart of the crystals of quartz ; being
palpably the same mica which is interspersed
through the granite. Sauss. 1621.

A granite, which Saussure says is of a new
formation, crystallised in the crevices of mica
slate, mostly composed of felspar, partly also with
quartz and mica. 1 267.

A granite, of which the quartz is of a lavender
blue, the felspar of a yellowish white, and the
mica, which is rare, of a dull leaden colour.
2144.

Granites with round crystals of felspar, like
that of Finland. 1195.

STRUCTURE II. OF A SMALL GRAIN.

White granite, with black siderite, from Mount
Sinai. On this, according to tradition, the Laws
of Moses were engraved.

Red granite of Egypt, passing in a vein through
grey granite, with patches of siderite, brought by
lloziere from the quarries of Syene.

which, from the sharpness of their angles, and other symptoms,
seem even to have crystallised apart. These are, rose-colour with
green spots, black with white spots, green and white, grey with red
spots, hrown with green veins.

02



DOMAIN II. SILICEOUS,



Grey granite, of quartz felspar arid siderite,
from Egypt. Wad.

Small or middling grained granite, with felspar



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