for engraving upon. They denominated it _smaragdus_, and are said to
have procured it from Ethiopia and Egypt; but, besides the true emerald,
Pliny, under this title, includes green jasper (96), malachite (231),
fluor spar (194), and some other green minerals. The pillars of emerald
in the temple of Hercules at Tyre, mentioned by Herodotus, and the large
emeralds described by Pliny as having been cut into columns and statues,
cannot be referred to the true emerald.
The deepest coloured and most valuable emeralds that we are acquainted
with are brought from Peru. They are found in clefts and veins of
granite, and other primitive rocks; sometimes grouped with the crystals
of quartz (76), felspar (110), and mica (123); and, not unfrequently,
loose in the sand of rivers. The most ancient emerald mine is that of
Manta, in Peru, but it has been some time exhausted; and most of the
emeralds that are now brought to Europe are obtained from a mine
situated in the valley of Tunca, between the mountains of New Grenada
and Popayan.
The emerald is one of the softest of the precious stones; and is almost
exclusively indebted for its value to its charming colour. The brilliant
purple of the ruby, the golden yellow of the topaz, the celestial blue
of the sapphire, are all pleasing tints; but the green of the emerald is
so lovely, that the eye, after glancing over all the others, finds
delight in resting upon this. In value it is rated next to the ruby;
and, when of good colour, is set without foil and upon a black ground,
like a brilliant diamond. Emeralds of inferior lustre are generally set
upon a green gold foil. These gems appear to greatest advantage when
table cut (Pl. II, Fig. 9), and surrounded by brilliants, the lustre of
which forms an agreeable contrast with the quiet hue of the emerald.
They are sometimes formed into pear─shaped ear─drops; but the most
valuable stones are generally set in rings. A favourite mode of setting
emeralds among the opulent inhabitants of South America is to make them
up into clusters of artificial flowers on gold stems.
The largest emerald that has been mentioned is one said to have been
possessed by the inhabitants of the valley of Manta, in Peru, at the
time when the Spaniards first arrived there. It is recorded to have been
as big as an ostrich’s egg, and to have been worshipped by the
Peruvians, under the name of the Goddess, or Mother of Emeralds. They
brought smaller ones as offerings to it, which the priests distinguished
by the appellation of daughters. Many fine emeralds are stated to have
formerly been bequeathed to different monasteries on the Continent; but
most of them are said to have been sold by the monks, and to have had
their place supplied by coloured glass imitations. These stones are
seldom seen of large size, and at the same time entirely free from
flaws.
The emerald, if heated to a certain degree, assumes a blue colour; but
it recovers its proper tint when cold. When the heat is carried much
beyond this, it melts into an opaque coloured mass.
The precious stone called oriental emerald (56) is a green and very
scarce variety of the oriental ruby.
68. _The BERYL, or AQUA MARINE, is a light or mountain green variety of
the emerald, sometimes straw─coloured, bluish, yellow, or even white._
These stones are of such frequent occurrence, even in large pieces
perfectly clear and free from flaws, they are in general so soft, and
have so little the brilliancy of other gems, that they are usually
considered of inferior value. The most beautiful kinds are brought from
Dauria, on the frontiers of China, from Siberia, and from Brazil. They
are also found in Saxony and the South of France, and are very common at
Baltimore, in North America. Specimens of aqua marine have been obtained
from the upper parts of Aberdeenshire, Scotland, where they sometimes
occur in alluvial soil, along with rock crystal and topaz. These stones
have also been found, embedded in granite, near Lough Bray, and
Cronebane, in the County of Wicklow, Ireland; and also in mountain rock,
in some parts of Devonshire.
They are cut by means of emery (58), and polished with tripoli (119).
The darkest green specimens are set upon a somewhat steel─coloured foil;
and the pale ones are either placed, like the diamond, on a black
ground, or upon a silvery foil. The aqua marine is usually made into
necklaces; but it is likewise employed for brooches, and not
unfrequently for steel stones and intaglios. The larger ones are in much
esteem among the Turks for the handles of stilettos.
69. _The TOURMALINE is a stone belonging to the same family as the
emerald, and generally of a smoky blackish colour: sometimes, however,
it is green, red, blue, or brown; and, when not very thick, it is
transparent._
_It is occasionally found in shapeless masses, but more frequently
crystallized in three, six, or nine─sided prisms, variously truncated or
terminated; and its weight is somewhat more than three times that of
water._
This stone was first made known in Europe, about the beginning of the
last century, by the Dutch merchants, who brought it from the island of
Ceylon, where it is principally found. When strongly heated it becomes
electric; one of the summits of the crystal negatively, and the other
positively. An early writer, by whom it is mentioned, says, that “it has
the property not only of attracting ashes from the warm or burning
coals, but that it also repels them again, which is very amusing: for as
soon as a small quantity of ashes leaps upon it, and appears as if
endeavouring to writhe themselves by force into the stone, they in a
little time spring from it again, as if about to make a new attempt. It
was on this account that the Dutch called it the ashes drawer.”
Since the above period, tourmaline has been found in Brazil; and in
Norway, Germany, France, and several other parts of Europe. It generally
occurs embedded in different kinds of mountain rock; and, in these, is
rather confined to single beds or strata, than disseminated through the
whole mass of the mountain. A piece of tourmaline, of cylindrical form,
and brownish grey colour, was some time ago discovered in the
neighbourhood of Kitt─hill, near Callington, Cornwall. Black tourmaline,
both in large and small crystals, is found in granite rock, in the
vicinity of the Logan, or Rocking─stones, near Treryn, in the same
county.
When laid on a table, the tourmaline appears a dark and opaque stone;
but, when held against the light, it has generally a pale brownish hue.
It is sometimes cut, polished, and worn as a gem; but, on account of the
muddiness of its colours, it is not in general much esteemed. Those
persons who wear tourmalines set in rings consider them more as objects
of curiosity than of elegance: they show them as small electrical
instruments, which, after being heated a little while by the fire, will
attract and repel light bodies.
In the superb collection of minerals of the British Museum, there is a
magnificent specimen of _red tourmaline_, or _rubellite_, which has been
valued at 1000_l._ sterling. It was presented by the King of Ava to the
late Colonel Symes, when on an embassy to that country, and was
afterwards deposited by the latter in Mr. Greville’s collection; with
that collection it became the property of the British Museum.
GARNET FAMILY.
70. _The PRECIOUS, or NOBLE GARNET, is a gem of crimson colour, which,
when crystallized, has the form of a twelve─sided solid (Pl II, Fig. 11,
12). It is sufficiently hard to scratch quartz, and is about four times
as heavy as water._
This stone is found abundantly in many mountains (particularly of
primitive rock), in different parts of the world. But garnets of the
hardest and best quality are brought from Bohemia, where there are
regular mines of them; and a great number of persons are there employed
in collecting, cutting, and boring them. The boring is performed by an
instrument having a diamond at its extremity, which is rapidly turned by
a bow. The work is so expeditiously performed, that an expert artist can
bore 150 garnets, or he can cut and polish thirty, in a day. In Suabia
there are two towns in which upwards of 140 persons are employed in
these operations.
In general garnets are stones of inferior value. When compared with the
ruby, those even of finest quality have a very sombre appearance. The
kinds most esteemed are such as have a clear and intense red colour, or
a rich violet or purplish tinge. The best garnets are cut in the manner
of other precious stones, and are usually set upon a foil of the same
colour. To heighten the colour and transparency of certain garnets,
jewellers either form them into what are called doublets, by attaching
to the lower part of the stone a thin plate of silver, or they hollow
them underneath.
Crystals of garnet sometimes occur three or four inches in diameter.
These are cut into small vases; which, if of good colour, and free from
defects, are highly valued. Many fine engravings have been executed on
garnet. One of the most beautiful that is known is a figure of the dog
Sirius, in the possession of Lord Duncannon.
The coarser kinds of garnet are used as emery for the polishing of other
minerals; and are thus prepared. They are made red─hot, then quenched in
water, reduced to powder in an iron mortar, and lastly diffused through
water, poured into other vessels, and allowed to settle, in order to
obtain an uniform powder. This powder is known to artists by the name of
_red emery_.
It has been conjectured that our garnet was the same kind of stone
which, on account of its colour, the ancients denominated _carbuncle_.
71. COMMON GARNET.—A very inferior variety of garnet, of brown or
greenish brown colour, is found in our own country, and particularly
amongst rocks near Huntley, in Aberdeenshire, Scotland. These garnets,
however, are, in general, so soft as to be of little value to the
lapidary; and consequently are seldom cut or polished for ornamental
purposes. But being easily fused, and abounding in iron, they are
occasionally employed as a flux in the smelting of rich iron ores: and
as an addition to poor ones.
72. SYRIAN GARNETS _are distinguished by their violet or purplish
tinge_. Some writers state that they have their name from the word
Soranus, which signifies a red stone; and others from Sirian, a town in
Pegu, where they are said to be found in great beauty.
73. PYROP GARNETS _are of a dark blood─red colour_, which, when the
stones are held between the eye and the light, falls strongly into
yellow: they are chiefly brought from Bohemia: are employed in almost
every kind of jewellery, and generally set with a gold foil. At
Waldkirch, in Suabia, there are twenty─four mills for the cutting and
polishing of pyrop garnets: and 140 masters are occupied in
manufacturing these stones.
74. VESUVIAN _is a liver─brown kind of garnet_, that was originally
found among rocks ejected from Mount Vesuvius; and in the vicinity of
which mountain it still occurs in considerable abundance. At Naples it
is cut into stones for rings and other ornaments. Vesuvian has of late
years been found in other parts of Europe; and even at Kilranelagh, and
Donegal, in Ireland.
75. CINNAMON STONE _is a kind of garnet of hyacinth─red colour_, which
is found in angular and roundish pieces among the sand of rivers in the
island of Ceylon. It is cut as a precious stone; and, when of good
colour, and free from flaws, is of considerable value.
QUARTZ FAMILY.
76. _COMMON QUARTZ is a hard and foliated substance, usually of white or
grey colour, and more or less transparent._
_It is generally found in shapeless masses, which are nearly thrice as
heavy as water, and the fracture of which is glassy. When crystallized,
it most commonly has the form of a six─sided prism, terminated by a
pyramid of six sides._
This kind of stone forms a constituent part of many mountains, and is
very common in our own, as well as in most other countries. It is
sufficiently hard to scratch iron and steel; and it has the property,
after having been several times successively made red─hot, and dipped
into water, of communicating to that fluid a certain degree of acidity.
Quartz is employed, in place of sand, for making the finer kinds of
glass; and also in the manufacture of porcelain. For the latter purpose
great quantities are collected from the mountains of Wales, ground into
powder, and in that state shipped to Liverpool, and other parts. After
having been burnt and reduced to powder, it is sometimes mixed with
clay, and formed into bricks for the construction of glass furnaces:
these are capable of resisting the intense heat which is requisite in
the fusion of glass.
77. BURRSTONE _is a vesicular and corroded variety of quartz, which
forms a most excellent and valuable_ _kind of millstone_. It is chiefly
found in France; but is so much esteemed by the English millers, that
the Society of Arts, in London, for many successive years, offered a
considerable reward for its discovery in Great Britain. At length a vein
of burrstone was discovered in the Moel y Golfa hills, North Wales, by a
Mr. Evans, who, in consequence received a premium from the Society.
About the same time another vein was opened near Conway; and the same
Society, in 1800, gave a premium of 100_l._ to the widow and orphan
children of the discoverer. Both these quarries were sufficiently
convenient for water carriage; yet the demand for the Cambrian burr did
not answer the expectation, and millstones of French production were
still preferred to them.
The mode of splitting these stones, as it is practised in some parts of
France, is singular, and affords a proof of the extraordinary power of
capillary attraction. The blocks are first cut into the form of
cylinders, sometimes many feet in height. To split these horizontally
into millstones, circular indentations are made round them, at proper
distances, according to the thickness that is to be given to the stones;
wedges of willow, that have been dried in an oven, are then driven into
the indentations with a mallet. When these have been sunk to a proper
depth, they are moistened with water; and, after a few hours, the
several stones that have been marked out are found to be perfectly
separated.
78. _ROCK CRYSTAL is an extremely beautiful kind of quartz, sometimes
perfectly transparent, and sometimes shaded with grey, yellow, green,
brown, or red. It occurs in the form of crystals with six sides, each
terminated by a six─sided prism._
The name of this substance was considered by the ancients to signify
ice, or water crystallized; and they imagined that crystal was produced
from a congelation of water.
Its uses are numerous. It is cut into vases, lustres, and snuff─boxes;
and many kinds of toys of extremely beautiful appearance are made of it.
When pure and perfectly transparent, it is much in request by opticians,
who make of it those glasses for spectacles which are called _pebbles_,
and who use it for various kinds of optical instruments. The best
crystal is imported from Brazil and Madagascar, in blocks, not
unfrequently from fifty to a hundred pounds in weight.
This stone is wrought into the different shapes that are required, by
sawing, splitting, and grinding. The sawing is effected by an extended
copper wire fixed to a bow: the wire is coated with a mixture of oil and
emery, and is drawn backward and forward until the operation is
performed. But, as this process is a tedious one, particularly when the
mass is large, a more expeditious, although less certain, method is
sometimes adopted. The crystal is heated red hot, and a wet cord is
drawn across, in the direction that the workman intends to split it. By
the rapid cooling thus effected, in the direction of the cord, the stone
easily splits by a single blow of the hammer, and generally in the
direction required. The grinding is performed by means of emery: and the
polishing effected by tin ashes and tripoli.
The ancients held vases that were made of this stone in great
estimation, particularly when they were of large size. Of two cups which
the tyrant Nero broke into pieces in a fit of despair, when informed of
the revolt that caused his destruction, one was estimated to be worth
more than 600_l._ of our money. The most valuable kind of crystal that
was known to the ancients was obtained from the island of Cyprus; but it
was often faulty in particular parts, having flaws, cracks, and
blemishes. When the crystal was used for the engraving of intaglios and
cameos, the artist could sometimes conceal these defects amongst the
strokes of his work; but, when it was to be formed into cups or vases,
this could not be done, and for the latter purpose the purest pieces
only could be employed.
In the counties of Cornwall and Derby, in the neighbourhood of Bristol,
and amongst the mountains of North Wales, small crystals of this kind
are frequently found: these are respectively called _Cornish_, _Buxton_,
_Bristol_, and _Snowdon_ diamonds. We are informed that the crevices of
some parts of Mont Blanc and the Alps contain rock crystal in such
abundance as to be perfectly bristled with it.
Some crystals contain in their substance drops of water, or other kind
of fluid; and these, as curiosities, are usually sold at a rate
considerably higher than others. There are in the British Museum
specimens of crystal which enclose many kinds of foreign substances,
such as ironstone, needle antimony, and asbestos (136).
Various means have been devised for communicating colours to rock
crystal. If it be heated and plunged into a solution of indigo, or
copper, it acquires a blue colour; or if into a decoction of cochineal,
a red colour. A clove─brown colour may be given by exposing it to the
vapour of burning wood. Artists sometimes communicate beautiful colours
to rock crystals, by forming them into what are called _doublets_. Two
modes of doing this are adopted. In one, a stone that is brilliant─cut
at the top is hollowed underneath, filled with the colour that the stone
is intended to exhibit, and then closed at the bottom by a plate of
glass. If this kind of doublet be dexterously executed, the deception is
not easily discovered; for the whole mass will appear of an uniform
tint. The second kind of doublet is formed by cementing a coloured plate
of glass on the base of a rose or brilliant─cut crystal: by this the
whole stone acquires the colour of the plate.
There are found in nature, many coloured kinds of crystal. These are
often confounded with precious stones; and, as such, are made into
female ornaments of different kinds. The following are the principal of
them.
79. COMMON AMETHYST.—_This is a violet─coloured crystal_, which acquires
considerable brilliancy in polishing, and is sometimes of sufficient
size to be formed into columns more than a foot in height, and several
inches in diameter. When the colour is good, and uniformly diffused,
amethysts are cut into necklaces, bracelets, ear─rings, and seals; and,
when less pure, they are manufactured into snuff─boxes. They are valued
in proportion to the depth of their colour, and to their perfect
transparency. The most favourite form in which they are made up is in
necklaces; and as it is not easy to find a number of perfect stones with
precisely the same tint of colour, necklaces of this description are
very valuable. The finest that is known was in the possession of her
late Majesty. When the colour is not uniformly diffused, jewellers
sometimes expose amethysts, for a little while, in a mixture of sand and
iron─filings, to a moderate heat; and, by this process, their appearance
is rendered more uniform.
The amethyst being almost the only coloured stone that can be worn with
mourning, it derives, from this circumstance, a considerable addition of
value.
This species of gem was well known to the ancient Greeks and Romans, and
was held by them in great esteem. Its name is derived from the Greek
language, and implies a power of preventing intoxication; which
(originating no doubt in the resemblance of its colour to that of wine,
and the absurd doctrine of sympathies) it was believed by the ancients
to possess. They ascribed to it many other virtues, equally surprising
and equally absurd; particularly that the wearing of it would expel
melancholy, procure the confidence and friendship of princes, render
people happy, and even dispel storms of wind and hail. The ancients
frequently engraved upon amethyst; and their favourite subject was the
representation of Bacchus and his followers.
The most valuable amethysts are imported into Europe from India and
Ceylon. These, although they are with truth denominated oriental, must
be carefully distinguished from the true oriental amethyst (55), which
is a much more valuable gem. The amethysts next in esteem are found in
Brazil, and are procured in the mining districts of that country.
Siberia, and various countries in Europe, especially Germany and Spain,
also furnish very beautiful amethysts; and inferior stones of this
description are even found in the mountainous districts of some parts
both of Scotland and Ireland.
80. FALSE RUBY _is a crystal of red colour_, and found in Bohemia,
Silesia, and Barbary.
81. FALSE, _or_ WATER SAPPHIRE _is a blue crystal_, which does not
differ much in appearance from the true sapphire, but is considerably
less hard. This kind is found in Bohemia, Silesia, and some parts of
Switzerland, but it is not so valuable as the last.
82. FALSE EMERALD _is a green variety of crystal_, the scarcest and most
valuable of all the coloured kinds. It is chiefly found in Saxony and
Dauphiny.
83. YELLOW, _or_ TOPAZINE CRYSTAL _is a stone of wine─yellow colour_. It
is found in Brazil and Bohemia, but has no other alliance with the true
topaz than its colour.
84. CAIRN GORUM CRYSTALS are obtained in various parts of Scotland, but
particularly from a mountain of that name in the county of Aberdeen.
_They are usually of smoky yellow or brown colour_, and are, at this
time, so much in request for ornamental articles of dress, that several
lapidaries have been induced to settle in Aberdeen, who are constantly
employed in cutting them for seals, rings, necklaces, brooches, and
other trinkets. When these crystals are of deep and good colour, they
are nearly as estimable as topazes; and, if clear and large, they are
sold at a high rate. The price of inferior seal─stones varies from ten
shillings to three or four pounds each; but those of superior beauty
will produce from five to ten guineas. Such specimens as have a pure and
full yellow colour are often sold for topazes. When they are muddy, the
lapidaries have the art of entirely dissipating the colour, and giving
them a transparent lustre. This is done by means of heat, which will
dissipate the colour of every species of crystal.
85. _AVANTURINE is a quartz, generally of reddish colour, sprinkled with
yellowish shining points of mica (123), which are dispersed through its
whole substance._
A French artist, some years ago, having by accident, or “par aventure,”
suffered a quantity of brass filings to fall into a vessel of melted
glass, afterwards found that it was admirably calculated for vases and
different kinds of ornamental work. Hence he denominated it avanturine,
a name which mineralogists have since applied to those natural objects
of which this production of art was an apparent imitation.
Avanturine is found in some of the countries bordering upon the White
Sea, in Spain, and some parts of France. In the late Leverian Museum
there was a piece which weighed near five pounds, and was unique both
for beauty and magnitude. It had been discovered in 1788, amongst the
ruins of the triumphal arch of Julius Cæsar in the valley of Suse, in
Piedmont; and was purchased of the person who found it for 200 guineas.
Avanturine is cut into various ornamental articles, which are sometimes
sold at a very high price.
Imitations of it are very common, and are formed by the simple operation
of throwing brass or copper filings into coloured glass in a state of
fusion.
86. _CATS─EYE is a stone of brownish grey colour, tinged with green,
yellow, white, or red; semi─transparent, and reflecting from its
interior a splendid white line or speck, which_ _varies according to the
direction in which the stone is held to the light._
_It is found in pieces that are rounded, massive, or blunt─edged._