Earths. MINER 
v 
ve&ions. Several of the mountains are, as it were, ftrewed 
with blocks of granite, which, at a diilance, appear as 
numerous herds of cattle; and it is this circumftance 
which is faid to have procured this ridge the name of 
Adon : lholo , a Mongole word, denoting “ herd-like moun¬ 
tains.” All theie detached rocks are fragments of the 
vaft ftrata of granite that compofe the greateft part of the 
Dauric mountains. The fummits of the Goatfield and 
other mountains of Arran have the appearance of huge 
walls compoled of large granite mafl'es. 
At Huelgouet, in Low'er Brittany, we are informed by 
Monnet, as alfo in the Vofges, enormous maffes of gra¬ 
nite are feen piled on one another, and forming moft ex¬ 
traordinary groups. The granite being here divided into 
maffes by Allures, which are filled up with granite pof- 
ie fling lefs folidity, this latter is fooner adted upon by 
atmofpheric agency, whence, by its difintegration, the 
maffes become perfectly detached, and adopt various po¬ 
rtions. But, befides the accidental groups formed by 
the rolling down of the rocks, there are other groups of 
granitic rocks at Huelgouet, that appear to be in their 
natural polition ; and many of them form an affemblage 
of rock-maffes, which have perfectly a rhomboidal form, 
and are regularly joined to each other by means of their 
correfponding planes. One of the infulated rocks in a group 
at Huelgouet, is called Pierre branlante , or the rocking- 
lione: it is twenty-one feet long, feven feet high, and 
<*ight feet w-ide, and its cubical content is 1160 feet: it 
is fo accurately polled on the edge of another rock, which 
ferves for its bale, that the ftrength of a few men fuffices 
to change its centre of gravity, and to communicate an 
ofcillatory motion to it. The phenomenon of roclting- 
Jiones is not unknown in this country; the largeft is that 
feen at the Land’s End in Cornwall, where they are called 
Logan-ftones ; it weighs upwards of lixty tons, retting on 
another rock of granite of confiderable height dole on 
the lea-ill ore. “ The two ftones,” fays Mr. Playfair, who 
avails himfelf of this phenomenon among others to ex¬ 
plain the migration of ttony mattes, “ touch bat in a fmall 
lpot, their furfaces being confiderably convex towards 
one another. The uppermoft is fo nearly in an equili¬ 
brium, that it can be made to vibrate by the ftrength of 
a man, though to overlet it entirely would require a vaft 
force. This ariles from the centre of gravity of the ftone 
being fomewhat lower than the centre of curvature of that 
part of it on which it has a tendency to roll; the confe- 
quence of which is, that any motion imprefled on the 
ftone forces its centre of gravity to rife, (though not very 
confiderably,) by which means it returns whenever the 
force is removed, and vibrates backward and forward, 
till it is reduced to reft. Were it required to remove the 
ftone from its place, it might be moft eafily done, by 
cutting oft'a part, or blowing it away with gun-powder; 
the ftone would then, lofe its balance, would tumble from 
its pedeftal, and might roll to a confiderable diftance. 
Now, what art is here fuppofed to perform, nature herfelf 
in time will probably eft'eft. If the wafte on one fide of 
this great inafs fnall exceed that on the oppofite in more 
than a certain proportion, and it is not likely that that 
proportion will be always maintained, the equilibrium of 
the Logan-ftone will be fubverted, never to return. Thus 
we perceive how motion may be produced by the com¬ 
bined adtion of the decompoiition and gravitation of large 
mafl'es of rock.” 
It was probably from feeing the fantaftical and imita¬ 
tive forms produced by granitic cliffs, and by the difin¬ 
tegration of granite, that M. Vitte framed his unfortu¬ 
nate hypothelis refpecting the pyramids of Egypt, and 
the-.ruins of Perfepolis, Palmyra, ail'd Balbec; all which, 
together with the temple of Jupiter at Girgentum, the 
palaces of the incas in Peru, See. Scc. were conlidered by 
that antiquary as productions of nature! 
The ule made of granite is manifold; it is employed 
for building, paving, fteps, for troughs in ftamping-mills, 
for millftones, &c. The ufe of granite for architectural 
A L O G Y. Earths. 407 
and economical purpofes, is perhaps no-where more am¬ 
ply difplayed than at Peterfburg, where not only the im¬ 
perial and other palaces, but .even ordinary dwelling- 
houfes, have their lower parts lined with flabs of granite. 
The left bank of the great Neva, from the foundery to 
the Gulf of Cronftadt, and both banks of the Fontanka, 
and of the Catharine Canal, are lined by high walls con- 
itrudted of fuch flabs of granite; as are many bridges over 
the Neva, baluftrades, Sc c. The pillars, ftairs, balconies, 
See. in the palace of Cronftadt, are almoft all of the finelt 
kinds of granite. Thole employed for ornamental archi¬ 
tecture are cut and poliihed by lapidaries; but thole in¬ 
tended for lefs delicate purpofes, fuch as common flabs, 
fteps, cylinders, troughs, &c. are worked by the peafants, 
particularly thole of Onoielk. The rock, which ferves as 
a pedeftal of the equeftrian ftatue of Peter the Great, at 
St. Peterlburg, is of granite : the block was originally 32 
feet long, 21 feet thick, and 17 feet high ; but, in order 
to give it its prefent fliape, imitative of a pifturefque na¬ 
tural rock, it has been much diminilhed in fize. This 
block was dilengaged from a fwamp, about forty verfts 
from Peterlburg : its weight was calculated to be above 
three millions of pounds. 
1. Granites iimplex, or Ample granite: confiding of 
felfpar and quartz. Found in the Subaudic, Swifs, Sibe¬ 
rian, and Scotch, mountains, and detached near Geneva. 
The component parts varyas to their predomination, but 
the particles of felfpar are. fometimes fo combined with 
tranfparent quartz as to referable Syriac letters. 
2. Granites genuinus, or true granite: confining of 
felfpar, quartz, and mica. This moft common kind of 
granite is found in primitive and fometimes in lecondary 
mountains in moft parts of the globe, in innumerable 
varieties of hardnefs, proportion, diftribution, and colour 
of parts. Sometimes it is found mixed with other mine¬ 
rals, as Ihorl, hornblende, cryftals of garnet, fteatite, and 
alumine. It melts in a high degree of heat, leaving how¬ 
ever the quartz unaltered. The felfpar is often lielh- 
colour; the quartz generally white, rarely greenifh. It 
takes a very high polifh; and on this account has for many 
ages been ufed in the architedlure of columns, palaces, 
churches, ;»nd various ornaments. 
3. Granites fyenites, fienite, or green-ftone : confining' 
of felfpar, quartz, and hornblende. Found in Egypt, 
Greece, Norway, Saxony, See. fometimes in large mattes, 
fometimes in fmaller granulations : the component parts 
vary much ; but the hornblende and felfpar generally 
predominate, and the quartz in very fmall proportion : 
the colour of the felfpar and quartz .is generally white, 
and the hornblende black or black-green. 
Mr. Bake well, who in the year 1812 was engaged in a 
mineralogical examination of the inexhauftibie mineral- 
wealth of Cham wood Foreft in Leicefterfliire, for the earl 
of Moira, (now marquis of Haftings,) difeovered, amqngft 
the granitic rocks of that diftridl, a variety of fienite'of 
Angular beauty, furpaffing that from Egypt, or the con¬ 
tinent of Europe. Like other ftones of this fpecies, it 
conlifts principally of hornblende and felfpar; the latter 
is of a pale-red colour, the former is cryftalline, and of 
a beautiful green, refembling fmaragdite. It exifts in 
large blocks, and might be applied to purpofes of orna¬ 
mental or fepulchral architecture, and fculpture. It is 
from this kind of ftone that the durable monuments of 
antiquity were conltrudled. 
Corjicnn orbicular granite. This beautiful rock (which 
probably belongs to the fienite formation) was difeovered 
by M. Banal, in the ifland from which it derives its name. 
Its compofition is very extraordinary; it has a bails of 
ordinary grey granite, which, however, in moft parts, ex¬ 
hibits a confiderable portion of hornblende. But what 
more particularly characterizes it, is a number of balls, 
of from one to two inches in diameter, each compoled of 
fe'veral concentric and perfedlly-paraiiel layers, the outer- 
moil of which, generally white, opaque, and two or three 
lines thick, is compoled of quartz and felfpar, blended 
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