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magnesian gem.

The deserts of Siberia are annually co-
vered with efflorescences of Epsom salt, so
as in the short summer to resemble snow.
The talcous rocks in general present a dis-
criminating character in their unctuous
appearance; they have however, in some
cases, been confounded with the argilla-
ceous, which occasionally assume the soft-
ness and silky lustre of the magnesian.
The presence of magnesia is often indi-
cated by a green colour.



MODE I. TALC,



301



Massive,



MODE I. TALC.

Of this beautiful substance, considered as a Distinctions,
rock, there are two principal structures : the
COMMON talc, which occurs in translucent Common.
leaves, sometimes as large as four or five feet in
diameter, and which chiefly comes from the
Uralian mountains of Russia, whence it is called
Muscovy talc ; and what may be called MASS-
IVE talc, consisting of minute scales, irregularly
agglomerated, as in the substance called the
chalk of Briancon, which, from its farinaceous
decomposition, and other circumstances, cannot
justly be regarded as a soft steatite, but must
belong, on the contrary, to this division. It
must at the same time be remarked, that the
deficiencies of all our mineralogic systems, con-
cerning so common a substance as talc, are not
a little surprising. The grave and profound
Walleri us justly confines the appellation of talc
to the two substances above mentioned ; but the
science has continued to suffer by the confusion
of two very distinct branches, petralogy and
lithology, every minute substance found in a
vein, or parasitic, disturbing the attention from
the grand features of nature. The magnesian



302 DOMAIN IV. TALCOUS.

rocks, in particular, have never been described
with that attention which their curiosity and
importance authorise.

STRUCTURE I. COMMON TALC.

Characters. Texture, finely foliated, and of a glassy appear-
ance ; level, undulated, or involved.

Hardness, cretic. Fracture, slaty. Fragments,
amorphous, rather sharp, but the corners easily
crumble into white powder.

Weight, pumicose.

Lustre, sliming. Translucent, semi-transparent,
sometimes transparent.

The colour is commonly a silvery grey, but
often also light brown ; and specimens of this co-
lour are found, though very rarely, with beautiful
metallic veins, or illinitions. It is also found of
various beautiful tints of green, sometimes change-
able, being reflected as it were through a white
surface.

#tes. It abounds in the Uralian mountains; and it

appears, from the accounts of Gmelin and Pallas,
that it sometimes may be said to form whole
mountains, while a mountain of quartz appears on
one hand, and a mountain of felspar on the other,
so as to present elements of granite on a vast
scale. Fine talc is also found in the mountains



MODE I. TALC. 303

of Tyrol, whence it was brought to Venice, and
when exported from that mart assumed the name
of Venetian talc. When calcined into an impal- Venetian tale,
pable white powder, it was found a far more inno-
cent paint for the ladies than bismuth, formerly
used, but which is apt to become black, from the
approach of sulphureous, and some other fumes,
or even perfumes. An accident of this kind, ope-
rating hysterically, as not unusual with the sex,
may have occasioned the invincible aversion from
perfumes entertained by the Roman females. But
as white is now rarely used, calcined talc is mixed
with carmine, to form an elegant rouge ; which is
laid on with a bit of cotton wool, and rubbed off
with as much ease as hair powder.

Molina's able account of Chili affords the fql- Of Chat,
lowing information :

" Muscovy glass is there found in the greatest
perfection, not only for its colour, but for the size
of the pieces which may be obtained. It is gene-
rally used for glazing, and artificial flowers. The
plates of this mineral, which are used for windows,
and which are here much esteemed, because they
are pliable, and less fragile than glass, are often a
foot in length ; and I am convinced they might be
obtained two feet, if a little more care was taken
in the quarrying. This substance is as white and
transparent as the best glass ; and it has a quality






304 DOMAIN IV. TALCOUS.

which seems peculiar to it, that of preventing pas-
sengers from seeing those within the apartments,
while these perfectly discern objects without. A
second kind of this glass is less esteemed, which,
though found in plates of a foot square, is spotted
with yellow, red, green, and blue; and conse-
quently is not used as . the former. It might be
called mica variegata."*

In the Swiss Alps a beautiful talc is found, of a
changeable green, on silvery white, with thin leaves
forming contorted masses, adhering to a magne-
sian rock. Talc also occurs in leaves of various
sizes, from half an inch to six or twelve inches,
in granitic rocks, where it supplies the place of
mica. When not larger than mica r it is here
called micarel, genuine mica being ranked among
the siderous substances. Mr. Kirwan has given
the name of talcite to a parasitic substance, in
the form of small scales, loose, or slightly co-
herent,
cimik of The gradation of the involved or contorted talc

.

of Swisserland, to the chalk of Brianon, or of
Dauphiny, is sufficiently apparent. The latter is
used by the French tailors in marking the shapes
on broad cloth, whence the name of chalk has.

* Molina, Stor. Nat. del Chili, p. 77- The French translation
is very inaccurate.



MODE I. TALC.

been improperly bestowed. The gold and silver
mica of many writers seem rather to be talcous or
micarel; as the large brown talc sometimes verges
to a golden colour, and it is suspected that no
iron is found in either.

The Muscovy talc has been used instead of
glass for windows and lanterns, especially on
board of ships, where it is not subject to be broken
by the firing of cannon*. It was formerly con-
founded with laminar selenite ; and both were
called glades Maria, or the ice of the Virgin
Mary ; as the latter is still called by the labourers
at Montmartre pierre de Jesus, because it served
as a glass before little prints of the Saints.

Aspect 1. Large foliated talc. White, from
the Uralian mountains.

Greenish, from Tyrol.

Brown, from the Uralian mountains.

The same, with metallic lines, red, green, and
blue, perhaps from the vicinity of copper-mines.

Aspect 2. Undulated. Of various tints, from

the same countries.



* It is the mica memlranatea of Wallerius, which he says was
brought from Archangel.

VOL. I. X



306 DOMAIN IV. TAZCOU3.

Aspect 3. Involved or contorted. White, from
St. Gothard.

Of a silvery white, and light green, from the
same.

I

Aspect 4. Mingled. Foliate'd talc, in small
plates, forming, with felspar and quartz, a very
large-grained granite.

STRUCTURE II. MASSIVE.

Massive talc, from the Alps of Dauphiny, com-
monly called chalk of Briancon ; as vulgar appel-
lations are never precise, a soft steatite is some-
times sold under that name : but the French tailors
are not to be so deceived, and the genuine craic
de Briangon may be had from them, leaving on
broad cloth a farinaceous illinition. It must how-
ever at the same time be observed, that when a
soft steatite is mingled with micarel, the impres-
sion will be somewhat similar to that of the chalk
of Dauphiny. Nay, micarel itself has been found
to decompose into steatite*.

The rock of soft scaly steatite, of a sea-green
colour, discovered by Saussure in the Roth-horn,

* Gmelin, Linn. 69, describes the Creta Brianzonica as mimi-
tissiml lamellosum; the soft steatite particuliz impalpalUiltts.



MODE I. TALC. 307

2157, appears to belong to this division. It is
mingled with grains of white felspar, and cal-
careous particles, which effervesce with acids.
It is so soft as to be~ almost friable, and splits
into level horizontal layers : this curious rock re-
poses on serpentine, and is surmounted by a mi-
caceous lime-slate, strongly impregnated with si-
derous earth.

Dr. Babington has the following varieties *:

" Composed of broad, shining, flexible folia^
closely compacted, and of a greenish white co-
lour (Venetian talc), from Zillerthal in the Tyrol.

" This, from being of a white colour when re*
duced to powder, and leaving a beautiful polish
on the skin, has long been employed as a cos-
metic. Mr. Hepfner found it to contain mag-
nesia 44, silex 50, alumine 6.

" The same, on the surface of semi-transparent
felspar, of a pale reddish white colour, and shining
fracture, from the same place.

" A polished slab of the same, of a pale green
colour, and intermixed with shining silvery lami-
na?, from Scotland.

" Of a slaty texture, and greenish white colour
(schistose talc), from Bareuth.

* Cat. St. Aubyn, 38.
X 2



308 DOMAIN IV. TALCOUS.

" The same, of a duller colour, and somewhat
more compacted, from Hungary. ,

" In thin undulating laminae, of a dark greenish
grey colour, from Fahlun, in Sweden.

" The same, more indurated, and of a shining
yellowish grey colour, from Zillerthal in the Tyrol.

" The same, of a divergingly striated texture,
and dark grey colour, from Scotland.

" Composed of small compacted scales (talcite)
of a white colour and silvery lustre, enclosing pris-
matic crystals of green quartz, from Dauphiny."

Karsten, in his catalogue of Leske's museum,
has the following :

" Perfectly apple green, mutably reflecting sil-
very white, talc, from the Venetian states. >

" Talc, reflecting from the apple green, slightly
into yellowish, from the same place.

" Massive talc, of coarse and small granular dis-
tinct concretions ; and the same, indurated, which
is mixed with a large quantity of emery, from
Ochsenkopf, at Sch war zen burg, in the Erzgebirge.
" A fragment of a talc nodule, the fracture of
which is very slaty, from Tyrol."



MODE II. TALCOUS SLATE. 309



MODE II. TALCOUS SLATE.

Texture, nearly resembling that of massivd Characters,
talc, but easily divides into undulated fragments,
of a quarter or half an inch in thickness, the feel
being extremely unctuous, as that of soft steatite
or soap-rock.

Hardness, cretic. Fracture, foliated. Frag-
ments, amorphous, blunt, and soft.

Weight, carbonose.

Lustre, glimmering. Faintly translucent on
the edges.

The colour is changeable, greenish or reddish,
mingled with silvery white. It is found in the
Swiss Alps, in Scotland near Portsoy, and in
many other primitive regions. Being of recent
observation, it is little known in books of mine-
ralogy. It may perhaps be the laminar steatite
of Wallerius, which he describes as of a grey
colour, and found at Norberg, Salberg, and Gar-
penberg in Sweden.

To this Mode may also be referred the follow- Taicpus slates

ot Saussure.

ing rocks, described by Saussure :

" The asbestiform steatite rested on a stone,
which Mr. Struve says had received from Wer-
ner the name of chlorite slate. But the speci-



310 DOMAIN IV. TALCQUS.

mens before me are evidently of a composite
rock.

" We there see schistose parts of a greenish
grey, sparkling, which have the form of small
scales of chlorite; but these parts are very re-
fractory, and do not yield the glass of chlorite.
They do not form the tenth part of the mass of
this rock, in which parts of real steatite, of a
greenish white, predominate, soft, translucent,
and perfectly characterised.

<f We besides find in this stone parts crystal-
lised in. little straight plates, rhomboidal, nearly
rectangular, of a greenish grey, extremely bril-
liant, almost of a metallic lustre, a little harder
than steatite in mass, but with a grey streak.
These plates lay on one another, and form in the
stone glistening spots of an irregular form, three
or four lines in diameter, and one or two in
thickness. Viewed with a microscope, the sepa-
rated plates appear transparent and colourless ;
but their reduplication renders them scarcely
translucent in mass. Under the blow-pipe they
show themselves very refractory ; they become
opake, and covered only on their edges with a
dark and brilliant am el. I cannot consider them
but as a species of rayonnant^ strahhtein, of Wer-
ner, much like that of 1437 3 though with some
differences.



MODE II. TALCOUS SLATE. 3] |

" As then this schistus results from the assem-
blage of different stones, all of the talcous class,
I call it composite magnesian schistus.

" 1917. The collection that Mr. Struve sent
to me contains a stone, with a label, which sig-
nifies that Mr. Werner had named it an indis-
tinct variety of chlorite slate. Perhaps in this
instance, as in the former, Mr. Werner assigned
the name from specimens different from what I
received. In fact these are still farther removed
from chlorite.

" The rock before me, and of which I possess
two large pieces, is of a black inclining to green,
Its fracture is laminar, with plates often undu-
lated, very thin, separable into very fine flakes,
the direction of which varies in different parts of
the same piece. This fracture is indifferently
bright, and of a lustre inclining to the unctuous,
as well as its touch. It is translucent on its *
edges, to the thickness of half a line; the very
fine laminae appear white and colourless : but
those which are thicker, when looked through,
appear of a beautiful leek green.

" This stone is soft, and may be scratched
even with the nail ; the streak being of a whitish
grey, but little brilliant. Moistened by the
breath, it exhales a strong earthy smell. Its
specific weight is 2,905.



DOMAIN IV. TALCOUS.



cc Exposed to the blow-pipe, this stone melts
with difficulty into a greenish grey glass, semi-
transparent, which forms a globule, of the tenth
of a line at most.

" It has therefore no resemblance with chlo-
rite, and, being obliged to give it a name, I have
called it laminar magnesian schistus.

" We find enclosed in this stone some clusters
of crystals of the rayonnant, or strahlstein, which
I have described in the preceding paragraph;
and some detached crystals of octahedral iron,
It is found at Weysler Stoude, in the valley of
Urseren."



MODE III. MICAREL SLATE.

Distinctions. This has commonly been confounded with
mica slate, and has the same general appear-
ance ; the spangles having however sometimes
more of the silver lustre, and in other examples
more of the unctuous cast of talc, than is ob-
servable in mica slate, where the magnesia is
strongly impregnated with iron. It has also
the usual adjuncts of talc, and seldom contains
garnet, or the other siderous substances, that are
found in mica slate. In decomposition, it some-
times forms plates or illinitions of steatite be-



MODE IV. STEATITE. 313'

tween plates of quartz. It abounds in all the
primitive countries, but has not yet been distin-
guished from mica slate.

Aspect 1. Micarel slate, from the bed of the
Ganges, near Sirinagur.
The same, from the Alps.
The same, from Scotland.

Aspect 2. Dendritic, from Spain.



MODE IV. STEATITE.

This substance so much resembles fine soap,
that in Cornwall, where it abounds, it is com-
monly called soap-rock.

Texture, compact, finely granular, and unc- Characters,
tuous.

Hardness, cretic. Fracture, sometimes un-
even, sometimes conchoidal. Fragments, amor-
phous, blunt.

Weight, carbonose.

Lustre, dull, unctuous, sometimes glimmer-
ing, with particles of micarel. Translucent on,
the edges.

The most common colour is white, sometimes
delicately streaked with red, so as perfectly to



314 DOMAIN iv. TALCOUS.

resemble marbled soap. It also occurs greyish,
greenish, and more rarely yellowish, and is some-
times dendritic, or spotted*.

Klaproth has analysed the steatite of Corn-
wall, of which he gives the following account:
or the The steatites of Cornwall (talcum smectis>

Lizard.

Linn.) occur at the Cape Lizard, in serpentine
mountains, which it cuts through in small, per-
pendicular, or rake veins. The finest sort of it
is white, with bluish" or reddish spots, resembling
marble. When fresh from the mine it is so soft
that, like soap, it may be abraded with the
knife. It is used in making porcelain. The
working of these mines is carried on by the
House of the porcelain-manufacture at Wor-
cester, which pays <20. sterling for the ton of
20 cwt., because the bringing it out to the day
is extremely uncertain and dangerous, the ser-
pentine rock breaking in so frequently. There
also occurs in these mines another sort of it, less
fine, and having spots of iron ochre ; as well as
a third, brown-red variety, mingled with green.
Not far from thence, &foiRuan minor > also in ser-
pentine, there is found both a grey-white and a
light slate-blue soap-rock, or steatite, and also

* The dendritic occurs in Saxony, and near Kildrummy, Scot-
land.



MODE IV. STEATITB.

a whitish steatite, crossed by calcareous spar,
which gives it a smooth shining fracture.

" It was the first, finest .sort of steatites, that
was the subject of the following analysis."

The result is, silex 48, magnesia 20, argil 14,
oxyd of iron 1, water 15*.

Da Costa has given more particular inform
ation concerning the soap-rock of Cornwall.

" The soap-earth, or steatites, is found in a
sandy creek, not much above a mile to the north-
west of the Lizard point : the sand is very
smooth and pleasant, of a mixed colour, light
and blue, and when the tide is out, affords many
turning and winding passages betwixt the rocks,
also blue, and the vast masses of cliff, which the
violence of the sea has separated from their mo-
ther land, and from each other. There are also
two grots, one called Kynas hole, into which
those sandy walks lead; but in them nothing
remarkable is to be found, not even marine
plants, it being altogether too often washed by
the tides on the surface of these rocks. There is
sprinkled here and there a smooth, fat, and seem-
ingly unctuous kind of incrustation, in 'colour
and feeling much like to the natural appearance
of bees'- wax, or tallow, and much of the same

* Anal. Ess. i. 462,



316 DOMAIN IV. TALCOUS.

nature with the white part of the soapy rock;
but whether it exudes from the crevices of the
rocks, several of which have little chinks (filled
with this heterogenous matter), capable of emit-
ting what they contain, or whether this sub-
stance is first washed off by the sea from those
veins, and is again returned by the force of the
waves, till it incrusts the rocks, time and further
inquiries only can determine."*

" Most of the stones within reach of the sea
are covered with an adventitious and most beau-
tiful enamel; red, white, green, yellow, in thin
lucid scales, sometimes riding on one another in
different crusts. In the eastern part of this
cove, as the Cornish people call it, or creek, the
substance of the rocks, and the sides of the cliff,
are more gritty, and being soft, crumbling, and
of a reddish colour, mixed with veins of white,
like marble ; and the purest, and most beautiful,
lying in veins like metals. It is here more par-
ticularly called the soapy rock; as, by its
unctuousness, smoothness, and variegations, it
greatly resembles the finest kind of soap.

" The veins of steatites are of different
breadths; some run under the sea, some to near
the top of the cliff, and some through the cliff



* Da Costa, 37.






MODE IV. STEATITE. 317

up into the country, and seem in their course to
cross the tin loads.

" Nearer the Lizard than the soap rock is
another cove called Pintrith, which affords a
greyish impure steatites, spotted with black.

". The new soap rock, lately discovered, is at
Gew Grez, or Grez cove, in the tenement of
Kynas, in Mullion parish : it is about three
miles from Mullion town, and about a mile from
the old soap rock, or cove, which lies farther
southward. The entrance into the creek or
cove is very steep, craggy, and horrid : on the
right hand (in descending into the creek) the
hills are crested with naked rocks, or cairns, as
the Cornish people call them : the sides have
also many, but they are small. About half way
down the cove, a very small current of water
traverses it, in a very serpentine manner, and
discharges itself near the load, or principal vein
of the steatites. On the right hand, as you de-
scend the cove, it grows more craggy and much
narrower ; and a few yards lower, on the same
side, lies the main vein or load of steatites. The
various sorts are all blended together in spots,
sometimes in greater quantities in one place
than in another. In the white and red veined
steatites, pieces of a compact, hard, slightly pel-
lucid, sparry substance, are frequently found:






318 DOMAIN IV. TALCOttS.

the main vein, or load, is about eight feet over 4 5
it does not consist purely of the steatites, but
also holds quantities of rubble, or fragments of
a hard, smooth, dusky, greenish, and red co-
loured talcy-like fissile stone, called by the in-
habitants a variegated killas. Some small pieces
of white spar are also met with, but rarely.
About two hundred paces higher, on the left
hand, I found a soft and very greasy straw-
coloured steatites : in the sides of the country,
that is, of the solid strata which enclose the
vein, and intermixed with it, lay a reddish brown
steatites, but the straw-coloured kind was in the
greatest quantity : further down, near the level
of the sea, the steatites load has been more regu-
larly traced, and makes a course of about four-
teen inches wide between regular sides : the left
hand side of the cove is quite perpendicular
and consists of a hard black stone, seemingly
divided into strata by small horizontal fissures,
placed at great distances from each other. The
other sides of the cove are more open and rugged,
the sea beats strongly into the creek, which at
low water has a small sandy beach."

Of this substance there are two very distinct
structures ; the soft, already mentioned, and the

* Da Costa, 37*






MODE IV. STEATITE. 319

hard. To the last the following interesting ob-
servations of Patrin chiefly refer ; and they are
the more freely extracted, because his works,
like those of Saussure, though of the greatest
importance to the science, have never been
translated, and remain new to the mere Englisu
reader.

66 There is often so little difference between
ollite and steatite, that Saussure, who was so
well acquainted with rocks, sometimes uses
these two denominations in speaking of the
same substance; or, at least, he calls steatite
the substance which forms the base or the paste
of ollite. The greatest^ or the only difference
which, in fact, exists between them is, that
steatite is a more simple and more homogenous
compound, and that it is also more unctuous,
than ollite.

" It may be said, that steatite is to the ol-
lites what corncenne is to porphyries. It is a
paste which contains crystals, or, at least, dis-
tinct particles, of mica, talc, sometimes of as-
bestos or amianthus; as the base of porphyries
contains crystals of felspar, schorl, and grains of
quartz. Steatite is even observed, as that of the
summit of Roth-horn, near Mount Rosa, which
contains grains of felspar; and this mixture also

rms ollite.



for



320 DOMAIN IV. TALCOUS.

ce A steatite is found in Corsica, which is
solid, of an even tissue, of a uniform olive-green
colour, semi-transparent and unctuous: it is
what the Germans call nephritic stone, on ac-
count of its resemblance to the jad of the river
Ott Amazons, which has that name by excel-
lence. This steatite is, with a slight difference
of colour, exactly like the lard-stone of China.

" Saussure gives the description of a steatite
of St. Gothard, which he calls asbestiform steat-
ite : it is very interesting, because it shows the
transition of one stone to another.

" It is of a grey, approaching to yellow or
green, and it much resembles asbestos, but its
fibres are much larger, softer, and more unc-
tuous. Its longitudinal fracture shows large
fibres, parallel to one another, irregularly pris-
matic, as much as three inches long: their lus-
tre middling, sometimes bright; but it is owing
to a bed of talc, which covers the fibres of the
stone.

" Its transverse fracture is uneven, splintery:
translucent on its edges: soft, and scratches with
the nail. The small fragments melt by the
blow-pipe into a black globule.

" It is then evidently, Saussure says, a species
intermediate between talc, steatite, and asbestos.

" Rome de Flsle mentions a greenish steatite






MODE IV. STEATITE. 321

of Corsica, crystallised in hexagonal plates,



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