MMMMMN GEMS GEMS NOTES AND EXTRACTS BY AUGUSTO CASTELLAN! TRANSLATED FROM THE ITALIAN BY MES. JOHN BBOGDEN. THE PROFITS FROM THE SALE OF THIS TRANSLATION WILL BE GIVEN TO THE GOLDSMITHS' BENEVOLENT INSTITUTION. LONDON : BELL & DALDY, YORK STREET, CO VENT GARDEN. 1871. LONDON : PKIXTED BY W. CLOWES AND SUN'S, STAMFOUD STHF.ET AND CHASING CROSS. CONTENTS. INTRODUCTION. General Observalions . . 1 Hardness ..... 5 Specific Weight ... 6 Brightness, Colour, and Transparency ... 7 Electricity 9 Fusion and Solution . .10 History and value of Gems . J.I Adularia 17 Aquamarina 20 Agate 22 Alabastrite and Alabaster . 25 Almandine 27 Amazzonite 28 Amber 30 Amethyst 33 Apatite 35 Argirite 36 Asteria 38 Ivory 40 Aveuturine 42 Axinite 44 Beryl 45 Boort, or Knotty Diamond . 47 Cacholong 48 Calcedony 49 Calcedonyx 51 Carbon 52 Cyanite 54 Cymophaue 55 PAGE Clorophane 57 Cocca di Perla .... 58 Shells 59 Coral 60 Corundum 63 Carnelian 65 Chrysoberyl 67 Chrysolite 68 Chrysoprase 70 Eock Crystal .... 72 Diamond 74 Brilliant 82 Historical Diamonds. . 90 The Artificial Diamond . 100 Jasper 102 Dichroite 106 Hematite 108 Epidote 108 Essonite 110 Enclasio 110 Fluorine 112 Gagat, or Greek Jet . .114 Jacinth . . . . - . . 115 Jade ....... 117 Jargoon 118 Girasol 120 Garnet 121 Hauyna 125 Idocrasium 127 Hydrophane 128 Hypersthenum .... 130 Iris 131 Jolite 132 Labrador 132 vi CONTENTS. PAGE Lapis-lazuli, or Lazulite . 134 Lava 138 Petrided Wood . . . .139 Lepidolite 140 Lumachella 141 Lunaria, or Moon-stone . 142 Malachite 142 Marquisite 145 Marble 146 Mica 147 Mosaic 149 Natrolite 151 Nephrite 151 Niccolo 152 Cat's-eye 152 Olivine 155 Onyx 156 Oolite 157 Opal 158 Owarovite 161 Touchstone 162 Pastes 163 Peridot 166 Pearl 168 False Pearls 175 Pyroxenum 178 PAGE Pisolite 180 Plasma 181 Porphyry 182 Prase 184 Quiritine 186 Rubellite 187 Ruby 188 Oriental Ruby . . .188 SpmelRuby . . . .192 BalaisRuby .... 195 Sard 198 Sard-agate 200 Sardonyx 201 Emerald 202 Emery 210 Spuma Marina . . . .212 Stalactite 212 Tourmaline 214 Topaz 215 Tripoli 219 Turquoise 220 Variolite 223 Vermilion 224 Sapphire 225 EPILOGUE . . 234 INTRODUCTION. GENERAL OBSERVATIONS. MINERALS consist of all those substances which have neither animal nor vegetable life, and are therefore devoid of sensation, existing merely by the power of aggregation or chemical affinity. The science which treats of minerals is called Mineralogy, and is divided into two distinct branches, viz., that which preserves the name, and treats simply of minerals with regard to their component elements, and Geology, which regards minerals pure or mixed, as they exist in nature and in relation to the soil. Mineralogy describes the individual quality of the various mineralogical species; geology treats only of minerals as constituent parts of the earth. Those minerals which are used ornamentally and are prized for their rarity are called Gems. In mineralogy, as in other departments of natural history, minerals are united in groups, forming great classes, which are divided into genera, species, and varieties. We are indebted to Theophrastus, philosopher of 2 GEMS. Lesbos, for the most ancient treatise on stones. The mineralogical part of the Natural History by Gains Pliny includes a list of observations, many of which are still useful and acknowledged in the science. But, mineralogy has only taken the name and position of a distinct and separate science in modern times. Bauer, the German (known by the name of Agricola, which he assumed in Italy, where he studied with the learned men who rendered it at that time the home of arts and sciences), wrote a work about the middle of the sixteenth century, ' De natura fossilium,' under which denomination minerals were then comprehended, and he was the first person who distributed them into distinct classes. In Italy, the works of Andrea Cesalpino, of Camillo Leonardo, of Abramo Portaleone, of Giovan Battista Porta, and of Giovanni Serapione were already known. Linngeus, who found the system of Agricola still 'in existence, wished to adopt a new classification for minerals, and was the first to introduce important observations on crystalline forms. In 1758, Cronstedt, a Swede, discovered the ele- mentary components of metals, and Werner, the Saxon, in 1774, gave some rules for determining mineral species in an empirical manner, and was able to define their character with great precision. After him, the celebrated Abate Haiiy, having dis- covered the laws which regulate the symmetry of crystals, shed great light on that science, which he thus founded on a more certain basis. INTRODUCTION. Chemical discoveries very much assisted the right classification of minerals, introducing in the science a new law, founded on analysis, which helped to confirm or slightly modify that which had been already es- tablished as to crystalline forms. Berzeliiis, Weiss, Becquerell, Ebelmen, Brewster, Mitscherlich, Brocchi, Spada-Medici, Pouzi, and a number of learned men of every other nation contributed to the advancement of the science. Now, the learned, generally speaking, divide minerals into three classes : the first contains combustible minerals; the second, metals; the third, lithoids or stones. These three classes are subdivided, as we have already remarked, into genera, species, and varieties. To the first class belongs the genus of carbonates, which is divided into four species, the first of which is carbon, properly so called, and of which one of the varieties is the cubic carbon, otherwise the diamond. The third class distributes stones into twenty-four different genera, which are subdivided into many more species and varieties. For the sake of brevity we shall refrain from giving the denomination of each of these twenty-four genera, or orders, as they are called by others. It is sufficient for us to know that amongst these orders are the alumina, the silicates, and the fluorites. To the alumina belongs the species of corundum, of which the ruby, the sapphire, and, in short, all so- called oriental gems are varieties. Amongst the sili- cates is pure silex or quartz, from which is derived 4 GEMS. the varieties of amethyst, rock crystal, plasma, agate, jaspers, obsedian, and opal; amongst the fluorites is the topaz; amongst the aluminous silicates are the species of garnet, emerald, felspar, and porphyry. Gems are found naturally under two distinct modes of composition. Some have the atoms arranged evi- dently according to a fixed law, and are called " crys- talline gems," crystallized gems and crystals. Others have very minute particles or molecules simply collected together, without constant regularity of form, and are called amorphous gems, from the Greek a, " without," /xo,o<>j, " form ;" all the gems that solidify, after having been in a fluid state, belong to this class : when they are found under condensed gelatinous forms like opals they are called porodine ; when they appear to have been condensed by ignition into vitrifications they are called "jaline," i.e., vitreous crystal; this in miner- alogy denotes a solid body, which presents naturally, and without the assistance of art, a many-sided figure, more or less regular, which varies almost infinitely. However, it must be remarked that these can be divided into six very distinct groups or systems, as follow : 1st system, cubic. 2nd , , square prismatic. 3rd , , straight rhomboidal. 4th , , oblique rhomboidal. 5th , , oblique prismatic. 6th , , rhombohedric. INTEO DUCT ION. 5 The natural characteristics of gems are : 1st. The properties derived from the nature of the substance itself; namely, hardness and specific gravity. 2nd. Those phenomena which are produced more immediately by some external influence ; as light, electricity, and heat. HARDNESS. In gems, hardness denotes not only tenacity, but also the greater or less resistance which they oppose to being cut, scratched, or polished by others ; thus, while the diamond from its small tenacity is easily broken, and does not give out sparks under the action of the steel, it is the hardest amongst gems, because it cuts all other bodies, without being itself marked by them. The hardness of gems, considered as the attraction of cohesion that is, in the power they have of resisting the blows they receive to break and divide them mechanically differs considerably in the same species, according to the direction of the cutting, the surface of the stone on which the trial is made, and its more or less perfect quality. Hardness, and not cohesion, is the basis on which general experience rests for determining to what species a given gem belongs. For such a purpose, practitioners adopt the file ; but the mineralogist rubs the stone which is to be tried against another, begin- ning with the hardest gem, which is the diamond, 6 GEMS, and thus forms, by comparison, a graduated table, which is useful afterwards for new trials and experi- ments.* In many crystals, perpendicular planes at right angles exist, and it appears that between these planes the cohesion is so slight that they can be separated with greater facility there than in any other place. This particular property is called " cleavage." In some gems it is very easy to ascertain the point of cleavage, hut in others it is found with difficulty. Many gems, as, for example, rock-crystal and emerald, will only break into irregular fragments. SPECIFIC GRAVITY. In order to determine the specific gravity of different bodies, distilled water is chosen as a means of com- parison. If it be a gem which weighs 17 carats in the air, and in the water but 12, there will be : Weighed in the air . . . . 17 carats, Weighed in the water .. 12 , , Difference . . 5 Now, dividing the weight of the gem 1 7 by the dif- ference 5, the quotient will be 17:5 = 3*4, which * MoLs has made a graduated table as follows : 1. "White talc. 2. Sal gemma. 3. Calcareous spar. 4. Fluoric spar. 5. Apatite. 6. Adularia. 7. Rock crystal. 8. Topaz. 9. Corundum. 10. Diamond. INTBODUCTION. 7 represents the specific gravity of the gem which has been put to the proof. It is often very useful to know the specific gravity of gems, as a means of determining their quality, and to prevent the danger of their being changed for others, similar in appearance but very different in value ; as, for instance, the diamond and the jargoon. In the case of cut and polished gems it is therefore of great use in ascertaining the class to which they belong, without the possibility of injuring them by the otherwise necessary operation of filing. The comparison of the specific weight of gems was, according to Emmanuel, known to, and practised by, the ancients, and certainly in the Indies, for many centuries, in order to ascertain the quality of a precious stone. BRIGHTNESS, COLOUR, AND TRANSPARENCY. Gems acquire more or less brightness, lively, varied colouring, and transparency, in proportion to their single or double refraction, and to the polarization of light. The brightness of gems may be distinguished as follows : I. Adamantine brightness; that which gives out the splendour peculiar to the diamond. II. Vitreous brightness; that which resembles glass. III. Eesinous brightness; that which shines as if the surface had been rubbed with oil. 8 GEMS. IV. Pearly brightness; that which resembles the particular light of a pearl. V. Silky brightness; that which gives the appear- ance of silk-stuff. The value of a gem depends principally 011 the beauty of its colour. The colouring material is generally composed of metallic oxides. The wonderful variety of colours in the gems, which more than all others resemble those of the solar spectrum, gave rise to the diversity of names which are often given to the same substance. The red corundum is the oriental ruby ; the blue corundum is the oriental sapphire; the yellow corundum is the oriental topaz. The bluish-green emerald is now called beryl. Quartz has many names; and more or less value in its different colours. There are crystals which not only have a varied gradation of the same colour, but also present three distinct colours. I possess a quartz in which the central disc is red, surrounded by a green zone, ending in a white band. Corundums have been seen in which shone red, blue and yellow ; and we sometimes see the tormaline variously coloured, watered, and marked with strange figures. In some gems the colour differs according to the reflection or transmission of light. The opal with reflected light is prismatic, and with transmitted light it is whitish. The tormaline with reflected light is red, blue, or some other equally bright colour, but with transmitted light it is olive. INTRODUCTION. 9 Many crystals present beautiful changes of light, when this is reflected in certain given directions, as in the Labradors, the moon-stone, and the Asteria. Minute crevices cause the iridescence, as in the stone called Iris. Many gems are more or less transparent ; that is, they possess in a greater or less degree the power of transmitting light; and, according to these degrees, they have different denominations. That stone is called " transparent " which, when placed before an object, does not impede its view. When the stone allows an object to be seen indis- tinctly through it, it is called " semi-transparent," and " translucent " when it allows the light to pass, but hinders the view of objects. ELECTRICITY. Electricity is produced in gems by heat, friction, or violence. In some gems it is caused by warming them at the fire, and then they are said to possess pyrelectri- cism. Electricity is produced by friction in the topaz, the amethyst, all quartz, the diamond, the garnet and emerald. Some crystals become electrical by percussion, as, for instance, the Iceland spar. Some stones conduct, others reject electricity, which in those cases is either positive or negative. The power of retaining electricity when produced is very variable in stones, and the time which elapses 10 GEMS. before they lose it forms a valuable mark of distinction amongst them. The Indians have for a long time been aware of this property peculiar to gems. The celebrated Haiiy speaks of it at great length, while describing many instruments used by him to certify the phenomenon. FUSION AND SOLUTION. The facility or difficulty experienced in melting or dissolving a gem serves to indicate the elements of which it is composed. The diamond alone will not dissolve, although it is combustible. All the corundums can be dissolved by means of borax, but with great difficulty ; the emerald, the jar- goon, and the spinel more easily. Caloric produces very different effects on other gems ; some change colour, others swell and crackle, and many others burn are changed into vitreous globules, into a kind of cement, into a powder ; and in some others phosphorescence is produced. Many other precious stones, besides the diamond, are incapable of injury by acids ; amongst these are the corundum and the spinel. Not a few change colour in acids, as, for example, the German agate. INTRODUCTION. 11 2. HISTORY AND VALUE OF GEMS. From the most remote antiquity, and previous to every historical tradition, men anxiously sought for gems, and it pleased even the most rude and savage people to use them as ornaments and signs of civil, military, or religious dignity. Of this we are certain from the discoveries made in the most ancient tombs of Asiatic, Tyrrhenian, and Egyptian peoples, where gems were found, differing in quality, but almost all cut and wrought in the same manner. It appears that sapphires, emeralds, rubies, pearls, as well as jargoons, garnets, and agates were the gems most anciently known and used. Before these, we find ornaments were used, of amber, glass, and enamel, together with bronze, gold, and silver ; whence we conclude that, although nature sup- plied man with very hard stones, which required no labour but that used in discovering and digging them out, he nevertheless applied himself first to the manu- facture of glass, amber, bronze, silver, and gold before using gems, perhaps on account of the difficulty of giving these a form suitable for armlets, necklaces, buckles, diadems, and rings. It is also remarkable that these ornaments of amber, as well as of glass, stone, silver, and gold have been found from the first, wrought in the same fashion in the tombs of Tyrrhema, Etruria, Egypt, Assyria, and Mexico. Whence in all parts of the world it has been 12 GEMS. found, according to the most recent discoveries and studies, that amber, bronze, glass, silver, gold and enamel have been always used first ; afterwards oxides and agates, in their natural state, but soon after en- graved ; and lastly gems, at first merely polished in their primitive forms, but finally engraved and in relief. The form of these ornaments and jewels was espe- cially similar in that primitive period, as much in Egypt, Phoenicia, and Assyria, as in Italy, Germany, and America. Amber was found in a variety of forms, because more easily fashioned; glass was always in perforated globules, which, when threaded, formed necklets or bracelets ; bronze, silver, and gold were' found in forms differing according as the ductility of the metal allowed fine and finished work. Agates, like glass, were pierced as beads, or made into " mar- gherite," flat, circular, oval, rhomboidal, or square. They were afterwards found engraved as cylinders and scarabaei, but also pierced : finally, gems were obtained in their natural crystalline form, but polished on the outer facets, to give them transparency and brightness, after which they were with much labour pierced, and at last engraved. With regard to gems, as to many other things, the ancients had uncertain, if not altogether false, notions, almost always mixed with foolish superstitions. Pliny and Theophrastus asserted in their writings that, in order to preserve health, it was useful to wear certain gems. Every one knows how universal was the use of auiu- INTRODUCTION. 13 lets, which, were generally gems to which secret or supernatural virtue was attributed, as that of giving beauty, youth, honour, power, and fortune. The twelve stones, which in the breastplate of the high priest of the Hebrews indicated the twelve tribes of Israel, are the same as those which, amongst the Romans, signified the twelve months of the year and the signs of the zodiac. They are 1 Jacinth. Dan. Aquarius. January. 2 Amethyst. Gad. Pisces. February. 3 Jasper. Benjamin. Aries. March. 4 Sapphire. Issacliar. Taurus. April. 5 Agate. Naphtuli. Gemini. May. 6 Emerald. Levi. Cancer. June. 7 Onyx. Zabulon. Leo. July. 8 Garnelian. Reuben. Virgo. August. 9 Chrysolite. Asher. Libra. September. 10 Beryl. Joseph. Scorpio. October. 11 Topaz. Simeon. Sagittarius. November. 12 Ruby. Judah. Capricornus. December. From an ancient Hebrew tradition we learn that when the high priest, on days of humiliation, asked the Most High to forgive the Israelites their sins, the precious stones of the breastplate cast an extraordinary lustre if the Lord graciously granted pardon, but became dull w^hen his wrath was great towards his people.* * Emmanuel, p. 28. 14 GEMS. The Indians believe that a diamond taken with them in their long journeys is a certain earnest of safe return to the bosom of their families.* In the East, the ruby is a stone of good augury, provided it is never shown to friends ; it presages evil when it has a blackish spot, f The same stone is given by the Chinese in token of sincere friendship. J Even in the present day the Persians believe that wearing the spinel causes joy and prevents evil dreams. Not a few people, even in Europe, think it very unlucky to receive the gift of an opal or to possess a sapphire. One of the principal deities of the Peruvians Es- meralda had a niche formed of an enormous emerald. || Now in speaking of the value of gems we must mention a term known to all, and commonly used to" distinguish broadly the most precious stones the term Oriental gems. In fact, the gems discovered in the East generally excel in beauty those found in the West. But the qualities by which precious stones are dis- tinguished from each other, and which in a greater degree prevail in the Oriental, are, as we have already stated, * Feuchtwanger, p. 149. t Ibid. J Ibid. Ibid. (I Ibid. INTRODUCTION. 15 1. Hardness. 5. Chemical composition. 2. Colour. 6. Crystalline form. 3. Clearness. 7. Earity. 4. Specific gravity. Therefore, according as these qualities, either all or almost all, are united in good proportions in the same gem, the higher is its value and the more it is prized amongst precious stones and feminine ornaments. Whence, in giving a list of precious stones according to the value at present attributed to them, the above- mentioned qualities must be taken into account, and allowance made for the different value caused by diver- sity of size, greater or lesser transparency, and so on. Thus, considering them as equal in quality, they may be ranked as follows : 1. Diamond. 10. Jacinth. 2. Ruby. 11. Amethyst. 3. Sapphire. 12. Jargoon. 4. Emerald. 13. Aquamarine. 5. Pearl. 14. Peridote. 6. Opal. 15. Chrysolite. 7. Turquoise. 16. Tormaline. 8. Garnet. 17. Eock crystal. 9. Beryl. 18. Agate.. Nevertheless, this is not the order in which our subject shall be treated, as there are many gems which can by no means with certainty be declared superior or inferior to others, because the supply of, and 16 GEMS. demand for them varying, cause also a change in the value at different times attributed to them. We shall, therefore, following the example of many other writers, adopt the alphabetical order* as the most simple, con- venient, and useful to those who wish to study this subject, although perhaps it is the least scientific in a mineralogical point of view. But we wish it to be understood that this work is not a strictly scientific treatise so much as a collection of useful and curious notes about all sorts of precious stones. * This order cannot be observed in the translation, the initial letters of some gems being different in English. AD UL ARIA. 17 I. ADULARIA. THIS stone is so called from Adula, the Latin name of Mount St. Gothard, as the best kind is obtained there, and particularly from that part called the " Monte della Stella." Adularia belongs to the felspars, of which it is the purest kind. Its crystals have one of the facets deeply indented in the direction of the greater diagonal. Their primitive nodus is an oblique prism with rhom- boidal sides, whose base is an oblique-angled parallelo- gram ; the secondary forms present an oblique prism with four facets, a large rectangular prism, a tablet with six facets, and a rectangular prism with six facets. Masses of rough adularia are found in which there frequently exist double crystals, and yet in this state of perfect union they have different degrees of hardness. Some also are opaque, others translucent or clear. This union of massed crystals causes the iridescence which often distinguishes those found in Italy, France, Germany, Norway, America, and the Isle of Ceylon. That which comes from the Monte Stella is trans- parent, and has whitish reflections tinted with green and blue ; some pieces shine with pearly light. Others c 18 GEMS. are of an iridescent green colour which resembles the eye of a fish ; which often, in very thin lamina, be- comes by reflection a pale rose colour. This gem is remarkable for its brightness, which may compare equally with that of pearl and glass. It is very easily worked, having three cleavages, and has double refraction. Its cleavage is perfectly concave. Being altogether destitute of electricity, it does not act on the magnetic needle. When exposed to the action of the blow-pipe it melts into a transparent white glass. Its specific weight is 2-5. The heat, 0-1861. The analysis of adularia gives Alumina .. .. .. ..20 Silex 64 Potash .. H Lime 2 Although adularia scratches rock crystal, it is less hard than quartz. It is very difficult to specify its precise hardness, as the same piece contains portions which, being iridescent, are naturally soft ; others of a milky whiteness, which are harder, and, lastly, others which surpass the rock crystal in resistance. This substance, which has so many peculiarities, and is so specially prized for the pearl-white reflections which seem to move about inside the stone when it is turned, frequently owes more to the art of the lapidary for its admirable eifects of light than to its natural ADULAEIA. 19 beauty. In commerce it has a strange multiplicity of names ; now it is adularia, again it is lunaria or moon- stone, sun-stone, girasol, fish's eye, water opal, or opal of Ceylon, according to the colours reflected. From Siberia we have a special quality which is of a yellow colour, sprinkled over all the surface with an innumerable quantity of small golden spots, produced by very small crevices in the lamina. The most beauti- ful, cut invariably into smooth beads, have reflections in form of a star, diverging from the centre, but are very rare. It is wrong to confuse this species of adularia with the Oriental aventurino, because, although it may have the same appearance, it has not similar hardness. The adularia from Ceylon is generally in larger pieces than that from St. Gothard, but it is not so bright. The brilliancy and slightly bluish whiteness of the moon-stone (lunaria) of Monte Stella are indescribable ; however, its value is diminished by certain oblique lines which cross it internally. It does not appear that the ancients used this felspar, nor do I believe that it can be engraved. Caire, never- theless, asserts that Pini had a head of Achilles engraved on a moon-stone by Grassi, and that it came out with extraordinary effects. He believes, however, that the ancient names of astrios, lapis specularis, and selenites, applied to this stone. 20 GEMS. II. AQUAMARINA. THIS stone is so named from its colour, which so much resembles sea- water. Like other gems, it is divided into Oriental and Western. Amongst those which, on account of their hardness, are called " Oriental," the most hard is merely a light blue corundum with a slight tint of green and yellow. It is easily known by its specific gravity, which is always above 4. This gem is very scarce, and it would have all the value of other corundums but for the colour which is common to a great number of other stones possessing little value. The others are found in the Island of Ceylon, and from it they take their name. They are of a deeper greenish- blue colour, which renders them somewhat different from the Western stones. Their specific weight varies from 3-549 to 3'908, and it is thought that their hard- ness nearly equals that of the Brazilian chrysolite. They resist the wheel more than the others, and their brightness exceeds that of the Western gems. These are very transparent, and take a beautiful polish not- withstanding their inferior hardness, which is less than that of the topaz. The specific weight is from 2-70 to I'll. They possess double refraction, but in a weak degree. The cleavage is brilliant and wavy, sometimes scaly. Their primitive form is an elongated hexagonal prism. They melt when exposed to fire and AQUAMAEINA. 21 lose their colour. They are found in Daouria, in the Uralian mountains, in Siberia, in the Altai mountains, and in America. When analysed they yield Silex 68 Alumina ,. .. .. ..15 Glucine .. .. .. ..14 Lime .. 2 Iron .. .. .. .. .. 1 Those from Brazil are at present most prized because they are most beautiful. The aquamarina of Saxony is a variety of quartz very little valued, and in that country it takes its name from the different stones whose colour it re- sembles; thus, the bluish is called aquamarina; the yellow, topaz ; and the olive, chrysolite. Great crystal- lizations of Western aquamarinas are found. That which was exhibited in London in the year 1855 was very beautiful. Caire possessed one which weighed five hundred and forty carats. Fine and beautiful aquamarinas are worth from four to five hundred lire * the ounce ; those which are beautiful, but small, are valued at but twenty-five. The ancients used the aquamarina in its natural state, and also engraved, and they tell us of several celebrated intagli on that stone. They knew it under the generic name of aquamarina, and perhaps they often confused it with the beryllus, of which Pliny says, " It has the same nature as the emerald, and is of a green colour." * A lira is about equal to 8f d. 22 GEMS. III. AGATE. So called from the Latin name, Achates (A'^ar^s), of the Sicilian river now called Drillo, on whose shores this substance is found. This term generally indicates a great variety of semi-transparent quartzes. Agates are found in almost every part of the earth. Some are found in the East, some in the West, and the difference of their constituent parts makes the specific weight vary from 2-5891 to 2-6901. The agate, properly so called, like that of Sicily, is naturally translucent ; less transparent than crystalline quartz, but yet less opaque than jasper : it is too hard to be scratched even by rock-crystal ; it takes a very good polish ; it is never found in regular forms, but always either in nodules, in stalactites, or in irregular masses. Nevertheless, the agate called chalcedony frequently crystallizes in rhomboids. The Sicilian agate is often of a pale or grey colour, veined in a variety of forms ; sometimes it is spread in reddish- violet spots. The " fasciatella " agate is like a sample of many agates united in a single piece, and disposed in bands close to each other like ribbons or belts. The bands are sometimes in right lines ; others are curved, and then of a circular form arranged round a common centre. Eye agates consist of those parts of the stone in which AGATE. 23 the cutting discovers circular bands of very small diameter, arranged with regularity round one circular spot. These circles are frequently so perfect that they appear to be traced by the compass, and consist of two or three, seldom of a greater number. The first round is white ; the second, black, green, red, blue or yellow ; the most rare are those whose circles are at equal distance from the centre. The tree, or dendrijica, agate, from the Greek So/Spov, a tree, is that in which the material being formed in successive strata, it has allowed access between the strata to metallic solutions, which, under the pressure of the air, and by the solidification of crystals, remain there in a metallic state after evaporation. It is called tree agate when the enclosed pieces repre- sent trees, and muscosa when the pattern resembles flies : very seldom are these two phenomena represented together on one piece. Agates are found containing impressions of different plants, and of what appear groups of herbs, bushes of box tree, and ramifications of various sorts. The tree agate of the East is superior to that of Europe ; the beautiful polish which it takes, and its natural brightness, contrast in a marvellous manner with the dark-coloured ramifications. When the colour of the plants is red, the agates are more valued, because more rare. Figured agates are greatly admired for the form of their spots. Towards the close of the last century they were much in demand, and brought a high price, whence they were eagerly sought for, and perhaps 24 GEMS. deservedly, on account of their singularity ; for they were discovered with such combinations of design as would appear impossible without a hand and mind to have executed them purposely. In fact, the figures formed by metallic oxides inside the agate do not exist in a natural state exactly as they appear when the stone is cut. The skilful artist often finds it necessary to cut away some lines, marks, or spots which would otherwise deprive the design of regularity ; whence it may be said that, in this respect, the lapidary resembles to a small extent the sculptor who carves the statue from the block, cutting away the superfluous parts. No little study and cleverness are requisite in deciding on the best treatment of the spots existing in the interior of the stone, and in executing the intagli so that they produce the best effect. Camello Leonardo da Pesaro states that he has seen a figured agate in which were distinctly represented seven trees on one even ground. Boe'ce de Boot declares that he possessed one in which a mitred bishop was designed ; on another Poujet saw a Turk; Caire had one on which was delineated a cock in an attitude of defiance. Crystallized agates are those whose mass is divided by numerous fissures into divisions, which are either square, triangular, or radiating. They are vitrified, translucent quartz. The agate xyloidina, so called from the Greek word vAov, wood, is that kind generally designated agatized wood. The Oriental agate is almost always transparent, and ALABASTRITE AND ALABASTER. 25 of a vitreous light ; its material is homogeneous, and resists acids, being harder than the Western agates. Agates of all sorts have the property of acquiring stains of every colour by artificial means; black is given by boiling the stone in honey, in olive oil, or in water and sugar, and afterwards in sulphuric acid, which carbonizes the oil and sugar absorbed by the stone. To give a red colour, protosulphate of iron is added to the sulphuric acid, by which means the iron remains oxidized. The bluish colour is obtained by using yellow prussiate of potassium, together with protoxide of iron. The Oriental as well as the Western agate, when much variegated, is used in works of art. We have beautiful fragments of cups, both smooth and carved, in this substance, which bear comparison with the most classical remains of the art, wealth, and magnifi- cence of antiquity. IY. ALABASTRITE AND ALABASTER. A WHITE chalk of very close substance is called alabastrite. It is a species of sulphate of lime ; specific gravity from 2*7 to 2'8 ; and in scientific language is called chalky alabaster: it is very different from true ala- baster, for which it is often mistaken. Much softer and more transparent than white marble, alabastrite excels it in whiteness, and its substance is more homogeneous. 26 GEMS. There are mines of alabastrite at Volterra, in Italy, and at Lagny, in France. It yields easily to the lathe, the file, the scalpel, and the graving-tool ; and very generally in Italy ornaments for common use are made of it under the name of Volterra chalk, and sold at a very low price. It receives a fine polish, although not equal to that of marble. \Vhen formed into a hollow globe, and reduced to a substance of extreme thinness, it acquires such transparency as to allow light to pass very pleasantly ; which, when transmitted through it, is more vapoury than that which passes through ground glass. Although generally white, sometimes it has a veining similar to that of the Oriental alabaster. It is easy to distinguish alabastrite from alabaster ; it is less resistant, and can even be scraped by the nail ; and being dissolved in acetic acid, gas is not disengaged, as is the case with alabaster, which is afterwards always of a colour tending to yellow. Besides, this latter is formed of a carbonate of lime harder than that sulphate which composes alabastrite. Alabaster is found in stalactites and stalagmites in the caves of calcareous districts ; and is there formed by the filtration of water loaded with carbonate of lime, often mixed with colouring substances, such as metallic oxides. The large masses of alabaster are produced from closely crowded stalactites, in which fresh nitrations of similar substance have filled the vacant spaces; and consequently stripes and various undulations are visible in their interior. ALMANDINK 27 Those alabasters are specially prized which have a white tint inclined to yellow, a beautiful semi-trans- parence, and veins of a milky white colour: this variety constitutes the Oriental, or antique alabaster. Next follow the yellowish sorts, having zones of various tints, but not differing much from the ground colour : to these varieties belong the veined alabaster, the onyx marble, and the agate marble. The ancients used alabaster and alabastrite for making certain vases for balm, without handles ; which on that account were called oAa/Saorpa, from the privative par- ticle a, and from Xa^avw, to take; whence arose the name given to these two stones. We have no proof that they made any other use of alabastrite ; but they used alabaster in many other ways. In this material we have Italian and Egyptian scarabsei, and very beautiful sculpture of the Eoman epoch. Y. ALMANDINE. THIS is a sort of dark red vitreous quartz, somewhat similar in colour to logwood. Some have called it violet-red spinel ; but this is an error, since it has not even the hardness of the amethyst. The red tourmaline of Ceylon has sometimes the same appearance, but not the same degree of electricity, and its light is not equally resinous. 28 GEMS. The specific gravity of almandine is from 2*571, which, together with its slight hardness, helps to distinguish it easily from other stones which resemble it. It is seldom found in large crystals, and it is so opaque, in consequence of its dark colour, that it is only transparent when placed between the eye and the light. Barbot declares that he has seen a very large speci- men, which seemed like an inferior garnet; and, in fact, it may be well compared with the red lava of Etna or Vesuvius. Generally, the almandine is confounded with one of the rubies which Pliny declares are found in Alabanda, and therefore named Alabandina. In fact, Boe'ce de Boot, copying the Eoman naturalist, says that " Alman- dines take a place between garnets and rubies, so that they appear to be darker rubies ; but they are more common than these, and have less vivid light." But such descriptions are not adapted to the kind of quartz now under consideration ; which is not only inferior to the garnet, but is placed lowest amongst the coloured clear quartzes, and has no commercial value. VI. AMAZZONITE. THIS stone, easily mistaken for green jade, on account of its colour, is nevertheless quite different, as it belongs to the felspars, of which it possesses all the properties. AMAZZONITE. 29 The amazzonite is absolutely opaque ; unlike the jade, it takes a very bright polish ; its colour is a beautiful pear green, and fixing the eye on it, the longer it is looked at the brighter and more beautiful it appears. Its material is compact; no pores are visible in it : it is, however, covered with very minute marks, in the form of little straws, which are of a lighter green. When it is grey-green, the marks are of a greenish- white ; and when the ground is of a darker green, the marks or points are very close to each other, and of a darker shade, although always to be clearly distinguished on the ground colour. They are found in both East and West ; in Siberia as well as in America. There are veins of it on the Eussian frontier of Mount Ouralska ; and the mineralogists of that country call it Krim-spaih, that is, green-spar ; which name is more suited to the substance than that of " stone of the Amazons," or amazzonite, as this name was not the result of scientific examination, but given because the stone was found at a short distance from the Eiver Maranon, or Amazon, near the savage American tribe of Eupinambas. It was known to the ancients, who procured it from the East ; but we are not certain by what name they particularised it. Caire speaks of a beautiful antique vase, made entirely of this stone, and which he saw in Florence. This gem, which is easily engraved, can be used with fine effect in every sort of precious ornament. 30 GEMS. VII. AMBER. ALTHOUGH amber is not a stone, all writers place it amongst gems, as well for its value as that it has been used ornamentally by almost every nation of the earth, from the remotest period, and anterior to every historical record. Feuchtwanger asserts that the Phoenicians sailed to the Baltic for the sole purpose of procuring amber there. I am of opinion with Italian archaeologists, that the Tyrrhenians, long before the Phoenicians, had explored those seas, and drawn from the coasts in- credible quantities of amber, with which they made ornaments of every kind and domestic utensils. This is proved by the vases, cups, spindles, and other articles of unknown use, collected by me from the necropoli of the very ancient Pelasgic cities of Italy. The Tyrrhenians, and afterwards the Phoenicians, exchanged this substance with the Greeks, who named it electrum, r/Ae/crpov. Homer says that the Trojan women wore necklaces of amber. It seems that the electrical phenomena which this material exhibits were observed by the ancients, since Talete, as a result of his observations, came to the conclusion that amber was animated. Philemon and Pliny thought it a fossil ; and the latter person said, " heat resuscitates amber." Tacitus, having observed that it often contains insects. AMBER. 31 believed that it was a vegetable juice, and from this it derives the Latin name of succinum or sap. People used it as an amulet, and it was administered as a drug. Even in our own day many naturalists have con- sidered amber a mineral ; but Sweigger and Brewster finally proved that it is a resinous gum ; that is, the fossil juice of a now extinct tree of the primeval period, called the amber tree. This substance is found in round nodules, which vary from the size of a grape stone to that of a man's head, and sometimes several of them are grouped together. When broken, one surface appears concave and the other convex; it is translucent and transparent; has single refraction, and resinous light. It is found in different gradations of colour, from greenish yellow to reddish yellow. It oxidizes in the course of years, and darkens into red, but its dust is always of a whitish yellow. It scratches chalk, but is scratched by car- bonate of lime. This substance, under the action of the blow-pipe, burns with a yellow or bluish-green flame, emitting a dense smoke having a pleasing smell, and leaving a carbonized residue. Warm oil bends and makes it pliable, but it does not melt so soon as other gums, as it requires the heat of 517 Fahrenheit. By distillation it produces an acid, which from its name is called acido succinico, and an essential oil named oil of amber ; whilsl in the retort there remains a brown deposit, known 32 GEMS. as amber resin, which is used as a varnish. Insoluble in water, it dissolves in alcohol, as also in a solution of subcarbonate of potass. Its component parts are carbon, hydrogen, and oxygen, with lime, alumina, and silex. Of a specific weight varying from 1*080 to 1-085, its power of refraction is from 1-365. Mixed with drying oil of linseed and essence of turpentine, it makes another excellent varnish. Amber is found thrown from the sea on the shore. It is gathered in great abundance by the fishermen on the Prussian coasts, after the autumnal tempests of the Baltic. It is also found in China and America; in small quantities in Sicily ; and in Catania a very singular kind, of a bluish colour. Even in France some is found. In Prussia, however, there exist numerous caves of amber, which are explored by practised miners at a depth often of more than one hundred feet. The amber of the mines differs from that of the waters only in being more brittle, and it is often covered with a thick crust of clay. Those ambers which contain insects take the name of insectiferous amber. The yellow amber cut in the form of beads, either smooth or in facets, is much used both in the East and West as a feminine adornment. In the East it is called Karabe, and used to ornament pipes, pistols, guns, daggers, and yataghans. AMETHYST. 33 VIII THE AMETHYST. THE amethyst, like all gems, is both Oriental and Western. The Oriental amethyst is a clear corundum of a violet colour, somewhat reddish and of an elegant velvet- like appearance ; very bright ; perhaps less hard than the ruby ; specific gravity 4 ; of weak double refrac- tion ; and it cuts deeply into the rock crystal. The Western amethyst can be distinguished from it by the fact that when rubbed it preserves vitreous electricity but twenty or thirty minutes, whereas the Oriental preserves it for many hours. The Western 'amethyst is a clear quartz, coloured violet by the oxide of manganese which it contains : of the specific gravity of 2*7, it crystallizes in the form of a hexagon, terminated at the two heads by a species of cone with six facets. These crystals are often in masses, and the base is always less coloured than the top. The cleavage in one of such masses appears fibrous and concave in crystals of small size. The colour is more or less dark, and does not resist fire. This gem possesses double refraction, but in a moderate degree. It is motionless under the magnetic needle. It may be remarked that amethysts are generally found in metalliferous mountains, and are always in combination with quartz and agate. This substance is found in Ceylon, Siberia, Kamtschatka, Arabia, Brazil, D 34 GEMS. Prussia, Hungary, Spain, France, and Italy. The Carthagenian Spanish amethysts are of a very "beautiful purple-violet colour, very similar to that of the Oriental, to which, however, they cannot compare in hardness. The Brazils supply some very valuable, which, when cut, are worth from 1000 to 3000 lire the kilogramme. There are immense lines of them at one hundred leagues from Bahia, but the difficulty of extraction and of transport has rendered them useless hitherto. Unpolished amethysts, in their ordinary condition, are very much prized, and it is easy to know what country they come from, because those from Siberia often have the points of the crystals mixed with chal- cedony ; those from the Brazils are fragments coming from considerable masses, partly fibrous and partly crystallized ; those from Hungary are under the form of crystals joined together in a strange manner, whilst the largest are surrounded by many others much smaller ; as to those from Mexico, they have the points of the crystals perfectly white. There remains a great number of antique engraved amethysts, and Pliny gives as a reason for this that they are very easily cut : Sculpturis faciles. The Western stones were preferred, but were generally of a pale colour and rather inferior quality ; and King asserts that an engraving on a dark stone may be suspected of being modern. Scarabaei, both Egyptian and Etrus- can, in amethyst, are rare. Koman intagli in this . stone, however abundant, are seldom of good execu- tion. APATITE. 35 In all ages amethysts were used as feminine orna- ments. With regard to their colour, lliny says : Ad ricinium crystalli descendent, albicante purpurce defectu. The Romans gave the name of amethyst to many different substances, beginning with violet corundum down to the purple garnet. Perhaps the name is of more ancient origin, therefore the vain Greeks inter- preted it as from their language because it was believed that he who drank from an amethyst cup was secure from the effects of any poison it might contain. Ar- pesani remarks that the name came from a, non, and /xe$v, wine ; or from a, and //,e0uo-K(o, to intoxicate ; and in that case it would refer to the other opinion held by the ancients, viz., that it was a powerful antidote against drunkenness. IX. APATITE. THIS mineral was thus named by Werner, from the Greek aTraraw, to deceive, on account of its deceptive colour, which resembles that of many other precious stones ; whence, before its nature was precisely deter- mined, many mineralogists were led into error. It contains ninety per cent, of subsesquiphosphate of lime, and the rest fluoride of calcium. It is found in hexagonal crystals ; its fracture is concave ; it has a vitreous lustre, of a sea-green colour, or bluish green, bluish violet, often white, and some- 36 GEMS. times red, gray, or yellow. It is sometimes trans- parent, and sometimes opaque. It resembles the beryl and emerald; its specific weight is from 3 to 3'235. In some specimens, especially in the white variety, a bluish opal tint is observed in the direction of the vertical axis. It is fragile. Some are phosphorescent in heat, others become electrical by friction. This substance does not melt under the action of the blow-pipe, ex- cepting at its extreme edge. It dissolves slowly in nitric acid, without effervescence. On account of the phosphoric acid which it contains when solid, it is very useful as a manure. Apatite is generally found in primitive rocks, tra- versing granite, serpent marble, and in the rocks of the spent volcanoes in Saxony, England, Switzerland, Norway, and many American countries, where there is a great trade in it as a material for enriching land. Asparagine, which is a yellowish, translucent variety of apatite, is found in Estremadura. AEGIPJTE. ARGIRITE is a stone only known in modern times by the description given of it by the ancients, who also named it argirodama and magnes, and it appears that in somewhat more recent times it was called argentina. Caire tells us, on the testimony of Theophrastus, that ARGIRITE. 37 argirite, or magnes, was a very lustrous stone, so like silver that it might easily be mistaken for it; its texture, and the large sized pieces in which it was found, allowed of its being formed, carved, and en- graved in every manner ; therefore the ancients made it even into vases, and it was much prized and used in many different ways. Hill observes that the precious stone which the Greeks named magnes was totally different from that which to-day is generally understood under the name which we translate magnetica. Kirman gives the de- nomination of argentine* to the schistose spar, which has a very bright pearly light. Haiiy, at the word Argentina, says : see moon-stone. Dutens believed that argentina was a resplendent girasol on a silvery white ground; but the description of argentina does not give us the characteristics of the girasol, which always has a little yellow inside, is semi-transparent and sometimes transparent, whereas the argirite was necessarily opaque from its similarity to silver. Caire says that by chance he became possessed of a hard stone, whose appearance led him to compare it with argirite, " which was thought quite lost, and had been sought for so long." He continued: " It is formed of very thin leaves ; a very bright silvery colour per- vades it, without the deviating hues which are seen in cat's eye." I remember two objects of similar form, of unknown use and material, like cornucopias terminated by two horses' heads, which were in the Campana Museum. 38 GEMS. They were of a whitish colour, and were much oxidized, whence, at first sight, it seemed a recent precipitate of silver ; but this was not so, as, under the action of light, they did not become darker, but always remained white. Now, might not these two cornucopise have been formed of the unknown argirite ? Mineralogists can see and examine them in the Paris Museum. XL ASTERIA. WE read in Pliny : " After opals, amongst white jewels, the asteria naturally takes the pre-eminence, because it has enclosed in it a light, like that of the eyeball, which it sends out, now from one place, now from another, as if moving about in the jewel, and' when placed facing the sun, it emits rays, whence its name." * Is it possible from such a description to understand what stone Pliny wished to particularise? The sole distinctive character such a stone bears is the property of sending out bright rays when it reflects those of the sun. But this property is common to many gems. I saw, some years ago, a large sapphire, very thick, cut smooth, of a whitish colour, and almost trans- parent, which in the sunlight presented a beautiful double star, therefore it deserved the name of asteria. * Nut. Hist, xxxvu. ix. 47. ASTERIA. 39 Caire saw in London a large Oriental ruby, which, when placed in the sun, gave out a luminous star, and he describes it as an asteria-ruby ; the star-reflecting diamond of the Mineralogical Museum, in the Jardin des Plantes, in Paris, would thus be an aster ia-diamond. There is in the School of Mines, in Paris, a star-reflecting opaline corundum, therefore it is also an asteria-corun- dum. It seems to me we may conclude from the above that in the present day it is not intended to give the name of asteria to one separate species of gem, but rather to use it as indicating the different character of various species. The imperfect knowledge of mineralogy pos- sessed by the ancients did not enable them to dis- tinguish the different species of precious stones by their essential characteristics; whence Pliny thought to describe and determine one single class by a quality which is common to many. The phenomenon with regard to which these conclu- sions have been drawn is the result of a particular combination of molecules, which may be formed in every gem crystal; and by means of a very convex cutting, it takes place under a given inclination. If the name of asteria is retained, we may be certain that the most rare are corundums, and that amongst these the azure, or sapphires, give the appearance of stars more brilliantly. 40 GEMS. XII. IVORY. ALTHOUGH ivory is an organic substance, and not mineral, yet writers on precions stones do not fail to speak of it as an article which at all times was largely used in works of art, and chiefly in ornaments of every kind. Ivory is well known to be the teeth of the elephant, among which some are so large as to weigh two hun- dred kilogrammes, to be about three metres long, and to have at the base a circumference of almost seven hundred and fifty millimetres. They are procured from Africa and the Indies. The negroes wage a war of extermination against elephants for the sole purpose of sending ivory to the Europeans. In art, ivory is divided into green and dry, exactly as in speaking of timber for workmen. Articles in green ivory please the eye most, because they are of a white but slightly greenish tint. Yellow ivory is inferior in value to the white, because it shows the beginning of decomposition : oxygenized muriatic acid and the steam and water of slaked lime nearly restore yellow ivory to its original whiteness. The ivory of the hippopotamus' teeth is very much valued, because it never loses colour. Ornaments of most beautiful design in ivory have been obtained from the ancient tombs, but, on account IVORY. 41 of their great antiquity, they were nearly decomposed ; but now means have been discovered by which their original consistency is restored. This is done by dipping them in a glutinous solution, such as, for in- stance, thin gum-arabic water. Burnt ivory, or ivory black, is usually put at the back of those diamonds which, not being of the purest water, are set in the manner technically called a notte, i.e., dark, and in that case helps to give them an admirable lustre. Fossil ivory has been excavated, of different degrees of hardness, but always recognisable by its thread-like tissue. Sometimes it preserves its natural colour ; at other times it takes various tints, according to the sub- stances amongst which it is found ; hence it would be easily mistaken for a turquoise or a fossil gem, if, when cut, the colour were the same as that of the surface. History tells us that Dipoenus and Scyllis, disciples of Daedalus, excelled in making statues of ivory and ebony. The statues of Diana and Tegea, also that of Ajax at Salamis, were entirely of ivory. The seats of the kings of Eome, and those of the consuls, were also of that material. According to Winckelmann, there were in Greece upwards of one hundred colossal statues in ivory and gold. Boethius the Carthaginian, Suidas of Naupacia, Parhasius of Athens, Phidias and Mys, were equally celebrated for this description of statuary work. I have seen antique works in ivory of the Tyrr- henian, Italo-Grecian, Etruscan, Roman, and Renais- sance periods, and they all gave an exact idea of the 42 GEMS. dominant taste in the various epochs, and are examples of the best style of each. XIII. AVENTURINE. IT is said that the accidental discovery of the arti- ficial composition of a red vitreous substance, sprinkled internally with bright gold-coloured filings, and similar to the quartz much used in jewels of the peruke period, caused the name of aventurine to be given to both, merely distinguishing them by the addition of artificial or natural. Scientifically speaking, one cannot, from such a term, understand one special stone, since the agate, jasper, chalcedony, rock crystal, opal, and even the commonest fluate of lime, exhibit at times the golden filings, and therefore, as with respect to the asteria, so with the aventurine, there are stones of every species, which receive this name from the accidental quality above mentioned. Thus Borson had a chalcedony covered internally with a golden sand : it was aventurine chalcedony. Bossi describes a garnet jasper with small golden dots : it was an aventurine jasper. In New Granada a similar stone was found, there called pentaura : it therefore is an aventurine stone. We are of opinion that the aventurine quartz is the stone described by Pliny under the name of sandastro : AVENTURINE. 43 " Which some people call garamantife. It is found in India, in a place of the same name, and also in Arabia. The greatest beauty consists in the drops of gold, which always sparkle inside, but never on the surface. Some people esteem the Arabic more than the Indian stones." * There are two qualities of aventurine quartz, of which the most common, which has marks of yellow mica, or Muscovy talc, is found on the shores of the White Sea, in some mines of Silesia, of Bohemia, France, and Siberia ; the other, more rare, has bright reflections from minute chinks, and is found in Spain and Scotland. Its specific weight is from 2*6 ; it slightly scratches rock crystal; has a bright light, does not acquire electricity from heat, and has no power over the mag- netic needle. The ground colour is generally russet- brown, but there are some of yellow, grey, reddish- white, and green with black and white marks. However, aventurine quartz has two different aspects, viz., semi-transparent and opaque : the first has the exact specific weight of 2-6670, the second 2-6426. The great demand for aventurine quartz, when it was fashionable, originated the idea of making the stone artificially. I do not believe that chance could, by an accident happening to a workman, make such a fine combination ; therefore, with many modern authors, I claim the glory for Miozzi, who, in the infancy of modern glass work, after long study, was the first to make an aventurine glass, which, excepting in hard- * Nat. Hist, xxxvu. vii. 28. 44 QJEMB. ness, excelled all other aventurine stones. lie, however, was jealous of his secret, which he carried with him to the grave. After many years, in 1827, another Venetian, named Bibaglia, with infinite labour and perseverance, suc- ceeded in composing a yellowish -brown enamel, tolerably consistent, but very easily melted, and superior to all other aventurine in beauty. Its analysis gives Silex 0-652 Phosphoric acid .. .. .. 0-015 Deutoxide of copper .. .. 0-030 Protoxide of iron .. .. 0-065 Lime .. .. .. .. 0-080 Magnesia .. .. .. .. 0-045 Soda 0-082 Potash 0-021 This, however, like all chemical analyses, is not the formula for the real composition of this substance. The sale of this beautiful product of Italian industry yields to our country, and especially to Venice, from fifty to eighty lire for every kilogramme of the rough material. XIV. AXINITE. THE name of this mineral is derived from the Latin axis, the edge of the axe, and was given to it because its crystalline form resembles that utensil. It is also BERYL. 45 called Thumerite, from the name of Mount Thumor, where it was first procured. It is found in great agglomerations, and in somewhat different forms, which may, however, all be reduced to the rhomboidal, that is, to an oblique rhomboid or prism with four sides, so much compressed as to make the angle so sharp that it resembles the edge of an axe. It is translucent, and sometimes transparent ; it has single refraction ; its light is vitreous and resinous ; its colour brown, violet- blue, grey, or yellow. It scratches glass, but is scratched by the topaz ; it yields a whitish powder ; its specific weight is from 3-27. It becomes electric when warmed or rubbed ; under the action of the blow- pipe it melts into a brown-grey glass ; acids have no effect on it, and it is composed of lime, alumina, and silex, with oxide of iron and manganese. It is found principally in primitive rocks, but also in others of different formations, in the Dauphine, in the Pyrenees, in Norway, and at St, Gothard. This mineral, espe- cially that from the Dauphine, takes a beautiful polish. XY. BERYL. THE stone which the ancients named beryllus is none other than that now called aquamarina of Ceylon, of which we have already spoken. Compared with other gems, the beryl is but little prized at the present day, being procured in great 46 GEMS. abundance, and found in all parts of the globe ; whereas the ancients had it only from India, and prized it as much as the emerald, with which they even confounded it; so that the enormous emeralds of which Theo- phrastus and Apion speak are now thought to have been aquamarina, as this stone is found in very large pieces. There are very few undoubtedly antique intagli in this stone, and they are as rare as those on the emerald ; the best, according to my experience, belonged to the Mertens collection. Generally the engraved beryls are Ionian work, whereas the engravings on emerald are Eoman. But although the Eomans did not engrave the beryl they facetted it, and it was the only stone they cut in that manner. They used it for ear-drops and rings. When the shade of Cynthia appears to Proper tius, he remarks that " Et solitam digito beryllon adederat ignis." Here we may remark, it appears that the ancients applied the term " beryllus " also to a magnifying glass, and perhaps they used aquamarina for the same purpose. This supposition is rendered probable from two reasons ; the first is that in the German ^language spectacles are called " brille," and no other derivation has been found for this word than the Latin " beryllus ;" the second is that Nero is said to have looked at the spectacle in the theatres through a very large emerald. We have already seen how easily the ancients con- founded the emerald with the beryl, and therefore we BOORT. 47 do not think it unlikely that Nero's emerald was an aquamarina cut for the purpose of a magnifying glass. In corroboration of the above, we bring to the notice of the reader the fact that Nicola de Cusa, Bishop of Brixen, who died in 1454, gave the name of Beryllus to one of his works for this reason, that " by means of its assistance, people could understand things other- wise incomprehensible ;" and in the second chapter he expressly says : " The beryl is a bright, transparent, colourless stone, to which a concave or convex form is given by art, and by means of which whoever looks through it sees things otherwise invisible to the naked eye." XYI. BOORT (KNOTTY DIAMOND). THIS particular species of adamantine carbon, which seems placed by nature between crystallized carbon and the pure diamond, bears a name of unknown etymology, but certainly of Dutch origin. Most frequently it is of spherical form, and its crys- tallization is so irregular that it resembles the most complicated knots in certain woods. It is a mixture of molecules without order or con- tinuity, and these, adhering solely by the force of cohesion, are the cause of its wonderful hardness. It has not any regular cleavage. The boort is externally more rough than some 48 GEMS. uncut diamonds; most frequently it is of a greyish white, and cannot acquire the diversified colours of the pure diamond, which it however exceeds in specific gravity. With us, it is only used to polish the regu- larly crystallized diamond ; and for this purpose it is pounded in a mortar, and its dust, mixed with oil, and spread over a surface of soft iron, renders the friction of the two diamonds more efficacious, and thus assists in obtaining the polish and splendour of the different facets. It is known that, whatever the variations of certain crystals, it is easy by means of their cleavage to reduce them to a regular determined form ; but in the knotty diamond this is impossible, as its texture does not permit of cleavage. The knotty diamond is found in the mines of Brazil, whence they are sent to Europe. Some people say that the boost is cut and used by the Orientals; but, even if this be so, they certainly have not in it a bright or valuable gem. XVII. CACHOLONG. A BARBAROUS name, not yet translated into any Eu- ropean language, and originating in Bokhara, from the words of its dialect, each, river, cholong, stone ; that is, " stone of the river." It belongs to the variety of the opal chalcedony ; opaque on the surface and of a milky CALCEDONY. 49 white ; when broken, the interior has a pearly reflec- tion, slightly translucent at the sharp edges. Harder than the opal, this substance takes a good polish ; it is unaltered under the action of the blow-pipe, and its specific weight is 2'2. The cacholong is found in separate bits in the rivers of Bokhara, in the Feroe Islands, in Iceland, in trapp rocks, and in Greenland. It is also procured in France ; and in Champigny, near Paris, it is brought from the caves of calcareous breccia, and some of it is hard, of bright cleavage, whilst others are light, rough to the touch of the tongue, and soft as chalk, and therefore of inferior quality, and to be regarded as imperfectly formed. There is a variety of this stone called striped, coming from Feroe and Ireland, which being composed of thin strata of white and opaque opals over strata of cal- cedony, often bluish or greenish, makes very fine cameos. Italian artists call it French stone. XVIII. CALCEDONY. THIS hard stone is thus named from the province of Calcedony, in Asia Minor, whence, in ancient times, it was procured in great quantities. It is a variety of agate quartz, generally of a milky- white colour, some- times bluish ; and this last tint somewhat increases its value. 50 GEMS. The calcedony is semi-transparent, but sometimes opaque and translucent. Its cleavage, although con- cave, is a little scaly and quite opaque, which helps to distinguish it from the carnelian, the sardonyx, the plasma, the chrysoprase, the onyx, silex and cacholong. It is found abundantly in uniform pieces or in strata within nodules of agate, and is round, uniform, sta- lactiform, primitive, rhomboidal, and seldom in crys- tallized cubes ; under this last form it encrusts crystals of shining quartz, of madrepore, of wood and of various other substances. It is not fusible, nevertheless the colour pales under the action of heat, but without producing water. Its specific weight is from 2*6. When analysed the result is Silex 84 Alumina .. .. .. ..16 Sometimes alumina gives place to lime. Like all gems, it is distinguished into Oriental and Western. This latter, less hard than the other and also than the white agate, is of a milky light ; it is common, and but 'little valued. There is one remarkable variety, which has red or grey dots on a striped milky ground, and is known by the name of stone of St. Stephen. According to Pliny, the fine calcedonies so much esteemed by the ancients came from Africa ; theyywere bought at Carthage, and then cut and engraved in Rome. CALCEDONYX. 51 At present this stone is found in France, England, Scotland, Ireland, Transylvania, Norway, Iceland, and the Feroe Islands. Those of a green colour are procured only in India, and are very rare. Those specimens, however, are particularly prized which contain a drop of water inside, although it does not always remain, as can be observed in some rock crystals, from which the water at last disappears by means of evaporation. The term " calcedonious stone " is applied to all gems having internally a milky tint. Eubies, sapphires, chrysolites, bluish diamonds, all diminish greatly in value when the term is applicable to them. The ancients used the calcedony very much in making valuable ornaments ; the primitive Babylonish seals, in form of the cylinder, and the latest Sassaman stamps, were formed of this stone. We also see Etruscan scarabaei and Greek and Roman intagli in this material. Statuettes of the period of the decadence of Roman art are found in this material, and it appears that bluish calcedony was considered better, and preferred for this kind of work. XIX. CALCEDONYX. THIS stone is very rare and little known ; its name is an abbreviation of calcedon-onyx. Its rarity therefore is 52 GEMS. the cause of the difficulty that exists in distinguishing it from the onyx agate, which it much resembles. It is much harder than this stone, but the difficulty of de- termining the degree of hardness without testing the stone prevents the possibility of deciding whether a given substance be really calcedonyx, except by the lapidary who tests it on his wheel. Barbot is said to have determined the specific weight of this substance, which according to him is 2'6180. It is often even more translucent than agate. It appears that it came from the East, and was not only known to, but engraved by the ancients, and these engraved stones are the only specimens in ex- istence of the calcedonyx, as, at present, none is found in any part of the world that we are aware of. In the ancient collection of Genevosio, Caire saw an engraved calcedonyx, representing a warrior seated op- posite a dead body. In the Viennese cabinet of en- graved gems there is another, which represents a young man leaning on a column. XX. CARBON. Bv this name, of which every one understands the general signification, we would specially indicate, tech- nically, a mineral substance discovered in Brazil in the year 1812, which was found mixed with deposits of diamonds in alluvial lands and in the mud of rivers. CARUON. 53 It is black, opaque, vitreous, of an irregular form, and of a specific weight of 3-782. Its most precious quality, and that which alone would distinguish it from every other mineral at all resembling it, is its prodigious hardness, which quite equals that of the diamond. This mineral, which is found in pieces varying from the weight of one to a thousand carats, has, since its discovery, been constantly used, in the same way as diamond dust, to cut and polish the diamond. It is also used in making certain graving tools capable of cutting gems of any degree of hardness. Sometimes pieces of this carbon are found which have an evident principle of crystallization, and pre- sent a number of small, bright, white points, which, however, are devoid of transparency. It appears that this is the raw material of the diamond before crystallization ; in other words, carbon, in the last stage of density. Xevertheless, we must ac- knowledge that this substance is different from the dia- mond, inasmuch as it cannot be divided in plates, which fact is explained by its non-crystalline composition. Subjected to a heat of 2765, it burns with a smoky, phosphorescent flame, much less clear than that of the diamond during combustion. After being a long time subjected to a great degree of heat, it is found, on withdrawal from it, to be of the same dimensions, of equal hardness, and still without transparency, although having lost all its black colour, and become greyish white. 54 GEMS. The carbon of which we speak can be cut into facets on the mill like the diamond, and, in that case, it reflects light while still remaining perfectly opaque. It is found in great abundance, and therefore can be had for from six to seven lire the carat. Its dust is preferable to that of the diamond, on account of its low price, and is found exceedingly successful in engravings on pietra dura and in cutting cameos. We must not mistake this substance for the ada- mantine spar of China. XXI. CYANITE. THE name of this stone comes from the Greek KVO.VOS, blue, which was given it on account of its colour. It has been known in various ages, and there is a tra- dition that it was wrought in England, under the reign of James I., by one Cornellius, a German artist, who called it seppara, which name it still retains in France. The tint of the cyanite is Prussian blue, and occa- sionally it fades from that to grey or green. It does not melt under the blow-pipe. It is trans- parent, and presents prismatic reflections, especially when cut smooth. Its specific weight is 3*5. It is not very hard, but scratches glass with its angles. CYMOPHANE. 55 When analysed, it yields, according to Barbot, Silex 43 Alumina .. .. .. ..55*50 Iron 00-50 And besides, it presents traces of potassium. The cyanite is found in granite, and in the micaceous schist of primitive mountains, either in masses or disseminated. The primitive form seems to be a quadrangular oblique prism, having watered, brilliant iridized facets. Easily broken, it has a double cleav- age, and is translucent and sometimes transparent. It is found in Asia, Europe, and America, and is also procured from St. Gothard and England. It is easily distinguished from the blue corundum or Oriental sapphire, although in India it is cut so as to imitate the latter gem, with the view of selling it deceptively at a high price. XXII. CYMOPHANE. THE name of this gem came from the Greek words Kv/jia " did not result in good works of art. LXI. MARQUISITE. SULPHURET of iron, in mineralogy and in jewellery, takes this name, which is to me of unknown etymology, unless we allow it to come from the French word marquis, which would in that case be the base of its name in that language, marquisite. As, at the time when firearms were invented, it was used instead of flint, it therefore took the name of pii ite, from the Greek 7rt>p, fire. The marquisite is found in large pieces, in the shape of a cube and the forms derived from it. It has a vitreous and very bright cleavage. It is found pure in various forms, including the hemispheric and dode- cahedric. Its specific weight varies from 3'900 to 4'954. When cut in facets like the rose diamond it is very bright. But all the marquisites in commerce are gene- rally small, not exceeding in size a gem of 2 carats. There are many varieties of marquisite, some tending to bronze, others to grey, or steel colour. When struck by the steel, it emits numerous sparks which exhale a sulphurous smell. Metallic, arsenical, and sulphurous particles abound, L 146 GEMS. more or less, in it, according to the mine from which it is extracted. It is also found with small portions of copper and very small particles of gold. It is obtained in the Alps, in Switzerland, Piedmont, and America. Peruvian marquisite is called stone of the Incas, because the ancient sovereigns of Peru attributed very great virtues to it, and wore rings and amulets which were made of it, and were enclosed with them in their sepulchres. They also used this material to make mirrors, and executed so muoh fine work in it as to give a high idea of their civilization. The most beautiful kind of marquisite, of a straw- yellow colour, comes from the Vale of Antigorio, near the Lago Maggiore, but it is rare. In the beginning of the present century marquisite was much used in feminine ornaments. LXIL MARBLE. ALTHOUGH marble cannot be placed amongst gems, nevertheless, as a mineral, having some affinity with them, I consider it well to speak of it now briefly. Innumerable are the minerals to which we might give the name of marble, but naturalists confine it to those only which are adapted for the chisel. The characteristics which divide and distinguish marble from porphyry and granite are three : first, MICA. 147 it is freely soluble in acetic acid ; in the second place, receives a mark from steel ; and, finally, it is reduced to lime by fire while giving out a great quantity of carbonic acid. Marble is partly composed of a sort of metal of ferruginous appearance, combined with carbon and oxygen. The proportions of its component parts vary according to the different qualities ; however, in general, it is equal to three- tenths of metal, one-tenth of carbon, and the remainder of fixed oxygen. The specific gravity of this substance varies from 2-650 to 2-850. The purest marble is always white, and the various colourations which form its different qualities are due to extraneous substances, either stony or metallic, the different arrangements of which modify it by the colour of its different tints. Marble of all kinds is amongst the productions which are most generally used in art and manufactures. But to. give their history and classification would be beyond our proposed limits. LXIII. MICA. FOR a long time, this name has distinguished certain substances capable of being divided into layers, which are elastic, very thin, translucent and fusible, of which the surface always remains bright, whence its name from 148 GEMS. the Latin verb micare, to shine. Some kinds of mica are known which have only one axis of double refrac- tion, attractive in some, repelling mothers. There are even some which have two axes, and present varied degrees of divergence. These peculiarities, which are easily perceived, on account of the layers being per- pendicular to the axis, indicate essential differences of crystallization, and also different species. Their com- position does not offer less difference ; some contain lithia, others potash, magnesia, or lime. Sometimes these substances are all united in it, in varied pro- portions. Black and dark mica is found, having in it a great quantity of peroxide of iron or of the corresponding oxide of manganese, and also of chromium. In general magnesian mica is softer to the touch, and always less elastic than the others. That kind having a base of lithia is frequently called lepidolite, as already remarked. Mica is often found crystallized, but only seldom under the form of regular crystals, which seem hexagonal prisms or oblique rhomboidrical prisms. Its specific gravity is 2' 7. It is found particularly in crystalline earths or in primitive rocks, and it may be said to exist in every part of the earth, being found in granite and in sand, in basalts and slates, in tufa, and in the latest deposits of tertiary districts. The colours of the different materials called mica offer every gradation of shade. There is the downy mica, which takes its name from the resemblance it bears to down. This effect is pro- MOSAIC. 149 duced by the diverging arrangement of its layers and its pearly colour. Finally, it is found in large folds or slabs, like that of glass which is used in windows. Mica, when of a good colour, could be used for many ornaments. The ancients, under the name of vitrum speculare, used great squares of this substance to exclude the air from their rooms, and very often fragments of it are dug out of ancient ruins. In Siberia it is still used for this purpose, and it is put, in place of glass, in Eussian ships. The glazing of the stove invented by Dr. Xott, of New York, is of mica. LXIY. MOSAIC. THE place which mosaic takes in feminine ornaments, and the material of which it is formed, induce me to say a few words about it, although most frequently it is composed of materials which cannot be strictly called gems. Mosaic is a work done in minute inlayings of glass, breccia, or agate, of varied colours, which, cemented together by a particular stucco, are formed into designs of all kinds, like colours on canvas. From this it may be easily understood that they may be divided into three classes, viz., mosaics in glass, mo aics in breccia, and mosaics in pietra dura. 150 GEMS. The most ancient works in mosaic are found amongst the Egyptian jewels. They consist of pieces of glass variously painted, and in enchased gold setting. Many pavements of the Greco-Romano period were great mosaics of -square marble of every colour. This work was called opus musivum. After the fifth century, mosaic was used in the walls and ceilings of churches, no longer in heavy marble, but in bright square enamels, united and supported by a stucco, over a great surface, with the utmost exact- ness, of which we have a splendid example in the Basilica Constantiniana of St. Sophia, and St. Mark's at Venice. In jewels of the period of Charlemagne, carnelian, plasma, and other agates have been found, set in gold, like the enamel of Egyptian work. In the seventeenth century, at Florence, and soon after at Dresden, they made mosaics of pietra dura, that is, of agate, jasper, and other gems, worked sepa- rately first into the desired form on the wheel, and then fixed with cement into gold, bronze, or marble, to form elegant tables, beautiful ornaments, or pretty feminine adornments. The mosaic workers of the Vatican, in the eighteenth century, began to make mosaics of glass, in very small proportions, and thus originated the so-called Eoman mosaics, which were and are still executed by artists of no little cleverness, who adapt this kind of work to every kind of ornament. NATROLITE. 151 LXY. NATROLITE. THIS mineral has been but recently discovered. It received its name from the Latin natrum, which means soda, because that alkali is its principal com- ponent. It has a rough breakage, is translucent at the edges, and of a pearly or white light ; sometimes deep red or yellow, and often in alternate zones. It scratches glass with difficulty, but can be marked by felspar. It produces a white powder ; has a specific gravity of 2'16 ; melts under the action of the blow- pipe, into a spongy, colourless glass; is composed of soda, alumina, silex and water; sometimes a small quantity of oxide of iron is mixed with it. Natrolite is found in Switzerland, Bohemia, Saxony, Scotland, and Nova Scotia. Natrolite, on account of the polish which it takes, has been used in jewellery, but it was not satisfactory, and now nothing is thought of this gem, so that it has no value in commerce. LXVI. NEPHRITE. See JADE. 152 GEMS. LXYII. NICCOLO. A VARIETY of onyx cut in such a manner that a zone of bluish white lies over a base of deep brown. This name is from the diminutive of onyx, viz., onicolo, whence niccolo, and not from the name of a certain Nicolo, perhaps an artist of the sixteenth cen- tury, as some assert. This stone, of little intrinsic worth, acquires value by being used in works of cameo and intaglio. It may almost be said that niccolo is a kind of onyx agate which has an extraordinary fineness of texture. Its specific weight is 2-590. Everything leads us to believe that niccolo is the Egyptilla thus described by Pliny : jEgyptiUam saccJius intelligit, per alvum sarda, nigroque venis transceuntibus : vulgus autem in nigra radice cceruleum facit.* It was often used by the ancients ; this is proved by the works of intaglio and relievo which have been found executed in this stone. LXVIII. CAT'S EYE. THE name of this mineral is derived from the peculiar play of light refracted by its surface, which resembles very strikingly the eye of the feline race. * Caire, 260, note. CATS EYE. 153 It consists of a quartz, mixed with parallel fibres of asbestos and amianthus. Asbestos and amianthus are two varieties of rnag- nesian silicates ; the first, rigid in its fibres ; the other soft and somewhat elastic, having a bright silken light and very fine fibres, easily separated and rather pliant. The ancients used asbestos to make lamp wicks fed with petroleum, and being incombustible it obtained the name which is derived from the Greek a-cr/2eViyu, (not to consume), incombustible. They wove the amianthus into a cloth, in which were wrapped the dead bodies they wished to reduce to ashes, because the amianthus being incombustible re- tained and preserved the ashes of the burned body. Besides, this material, becoming purified by the action of the fire and remaining in, it separated from every organic element, did not, in the operation, take any blemish, whence its name of amianto, from the Greek a, privative, and /ueuVco, to stain. The cat's eye is found in pebbles and in pieces more or less round ; it has a concave breakage ; is trans- lucent and also transparent at the edges. It has a vitreous and resinous light. It is generally either green, red, yellow, or grey. It marks glass. Its specific gravity is from 2-560 to 2-730. When exposed to a great heat, it loses lustre and transparency, but does not melt under the blow-pipe unless reduced to minute fragments. On analysis it gives 154 GEMS. Silex .. .. 95-00 Alumina .. .. 1'75 Lime .. .. 1'50 Oxide of iron . . 25 Cat's eye is found in pieces which are never larger than half a walnut; it is found in Malabar, in the island of Ceylon, in the Hartz Mountains, in Bavaria and in the United States of America. The finest come from Ceylon. We must be careful not to confound them with certain iridized agates which come from Arabia and Persia and much resemble them, but are softer, of a finer texture, and have brighter colours. In order to make them shine more brightly they are cut like the asteria, but the mineralogist assigns them a higher value in the rough state. It is not known whether the ancients were ac- quainted with this gem, or whether it was included in the asteria. The Moors and the Malabarese, from the remotest time, have held this stone in great veneration. In every country of the East it is worn as an amulet, which procures riches to the possessor. The Indians believe that the largest and most beautiful have this virtue in an eminent degree. Cat's eye, on account of its hardness, is well suited for engraving, but its colour, and the fact of its being iridized, only adapt it for such designs and ornamental figures as have been executed on this stone from the sixteenth century to the present time. OLIVINE. 155 LXIX. OLIVINE. SILICATE of magnesia, \vliicli receives the name from its colour. It is like the chrysolite, but less transparent and less hard. It is coloured with iron. It is found in masses and also in round pebbles, as frequently in France as in Italy, Scotland, Bohemia, Ireland, on Vesuvius, and in many other places. The cleavage of the olivine is imperfectly double, and its breakage is unequal and granulous. Its specific gravity is equal to 3-240. Analysed it yields Silex .. .. 50-00 Magnesia .. .. 38 '5 Lime .. .. 00-25 Oxide of iron .. 12-00 Subjected to the action of the blow-pipe, with the addition of borax, it forms an opaque button of dark glass: When put into concentrated acetic acid it loses colour; this phenomenon indicates a great porosity, most rare in the texture of gems of this kind, and a principal sign by which to distinguish it from those which resemble it. Olivine is found in pieces large and small, in basalts, in porphyry, and in lava: it is almost always with pyroxenic augite. 156 GEMS. The Vesnvian olivine is crystallized in long striped prisms. This stone is not much thought of, and there- fore of little value. LXX. ONYX. A VARIETY of quartz having a regular alternation of strata more or less even, and variously coloured in black, white, brown, grey, yellow and red. Its name comes from the Greek word 6Vv, nail, on account of the similarity which is found to exist between the arrangement of its strata and that of the human nail. When an onyx has one or two strata of red carnelian it is more valued, and takes the name of sardonyx* In the onyx the dark strata are always opaque, and contrast strongly with the clear, which, when thinned, become almost translucent. There are Oriental and Western onyx. The Oriental onyx is extremely hard, and of very fine texture ; acids have, in general, very little action on it. When in this mineral substance are found united neat lines, straight strata, and bright colours, it is of a relatively high price, especially if it has more than four fillets. The Western onyx, and especially that from Germany, is softer than the Oriental, and is deteriorated by acids, which alter the colour. Industry turns this peculiarity OOLITE. 157 to good account, and gives the stone a higher value. This onyx is worked principally at Oberstein, in Ger- many. Lapidaries formerly chose, and now prefer, executing their Arabian and Indian onyx work in that place, and the best camei are composed of that beautiful mineral substance. The low price of German stones causes them to be much used now. The ancients used the onyx engraved or simply cut, and very many of both kinds are still to be seen. LXXI. OOLITE. THIS mineral is a calcareous spar composed of very minute spherical particles, whose cohesion depends on a calcareous substance which acts as a cement. Its principal component is carbonate of lime. The name it bears is derived from the Greek (ioV, ovum, on account of its similarity to the spawn of fish. The oolite is found in pebbles or in masses. It is white, red, brown, or yellow. Large ridges of it are found in France and England. Cut and polished it is a fine marble, and it is used in ornamenting houses, as may be seen in many houses of the city of Bath, in England. 158 GEMS. LXXIL OPAL. THE gem is a hydrated silicate, insoluble in acids, and when subjected to a strong heat it becomes white, leaving a remarkable quantity of water. It possesses the property of reflecting all the coloured rays of the prism, and this property originated its name, derived from the Greek OTT, root of OTTTW, (obsolete), to see, and aAAos, other, in allusion to the multiplicity of its colours. The changing lights which it emits are caused by an immense quantity of minute fissures. In general it is injured by potash. It shows no trace of crystallization, or of double refraction. Its light is almost always resinous. It is found in scattered pebbles and in veins within a matrix of a reddish tint spotted with white, in trachytic districts. Its hardness varies, although it always yields to the file ; it is of very fine texture, and takes a beautiful polish. Very brittle, its breakage is bright and per- fectly concave ; it does not melt under the action of the blow-pipe, but crackles, splits and loses colour. When just extracted from the damp earth, the opal is very soft and destitute of light, but the air and sun soon succeed in giving it various degrees of beauty and consistency ; and it is a very curious phenomenon to see it sensibly hardening and the colours being created as the water evaporates from the minute OPAL. 159 chinks, in which, the air immediately takes its place. This phenomenon is very clearly exhibited in the Hungarian opals. It only preserves its brightness in a temperate at- mosphere ; and although sometimes it is placed in the sun that its iridescence may be increased, it spoils if left in it too long. In such a case, the bubbles of air contained in the internal chinks evaporate, and with them the colours depart ; the same thing happens in an intense and prolonged frost. Although, mineralogically, the opal may be divided into seven varieties, according to the countries where found, viz., Arabia, Ceylon, Hungary, Iceland, Scotland, Ireland, and Mexico, yet it has been generally agreed to distinguish it into three principal kinds, namely, the noble or Oriental opal, the fiery red or Mexican opal, and the common opal. The noble or Oriental opal is called harlequin, on account of its many colours, which shine in triangular reflections. Its hardness, and the softness of its colours are remarkable. Its specific gravity is 2*95. When analysed, it yields Silex .. ..90 Water 10 It came formerly from Arabia, but now it is procured in Upper Hungary, amongst the porphyry ridges. The Mexican fire-red opal, known also under the single name of Mexican opal, was, not many years ago, discovered by Humboldt. It is found at Zimapan, in 160 GEMS. Mexico, in a variety of trachy tic porphyry, and in the Faroe Isles in amygdaloid. Although beautiful when just separated from the matrix, it loses much when exposed to the damp and air ; when immersed in water, it comes out quite trans- parent and dull, but it partly re-acquires its fire when dried. Placed on the tongue, it leaves a disagreeable taste, by which it is easy to distinguish it from other varieties. When looked at against the light it is quite trans- parent ; in the solar rays it appears iridescent in a peculiar manner. Its specific gravity is 3*12. By applying to its surface a thin layer of olive oil, its brightness is increased, but only for a short time. It gives, on analysis, Silex .. .. 92- Water .. .. 7 '75 Iron .. .. 0-25 The common opal is found in great masses, in pebbles and in stalactites. Its breakage is concave ; it is trans- lucent and sernitransparent. It is found of various colours, milky, yellowish, whitish green, red, and wine red. Sometimes it is dendritic. Its specific gravity is between 1'90 and 2-10. It is composed of Silex 93-05 Water 5 Oxide of iron . . 1 OWAEOVITE. 1G1 It is met with in veins along with the Oriental opal, in argillaceous porphyry, and sometimes in metalliferous ridges. The opal in general cuts smooth and full, whether in an oval lenticular form or as a drop. Fine opals are always set clear, as those set other- wise easily deceive the eye. It is well known that black increases very much the natural or artificial fire of the opal ; and this is so well known, that sets of opals in commerce are always presented on a smooth, bright black card. The common opal is of very little value ; the Mexican red is of less ; and the Oriental is very much esteemed. The opal was well known to, and appreciated by the ancients. Pliny tells us that it was found only in India. Everybody knows that the Roman senator Nunio preferred enduring the penalties of exile rather than yield a very beautiful opal to the rapacious Mark Antony. The Indians valued it as much as the diamond. This gem does not take engraving well. LXXIII. OWAROVITE. A SORT of garnet thus named in honour of one Owaro- vit, President of the Imperial Academy of Science at M 162 GEMS. Petersburg, to whom it was dedicated by the scientific Hess, who first studied it and gave it a distinct place. It is very similar to the green garnet, but harder. It is found at Bissersk, in Siberia. LXXIV. TOUCHSTONE. TOUCHSTONE is a black, hard, rugged schist, of very fine close texture. More than any other stone, it preserves marks of whatever metals are rubbed over it; this property gained it the name of touchstone, or stone by which the qualities of the different precious metals may be tested. This mineral substance, also called Lydian stone, is somewhat attracted by the magnetic needle, and dif- fuses a clayey odour when bathed in warm water. It takes a good polish, and is not hurt by acids. Its specific gravity is 2'415. Although the touchstone is generally black, it is also found of an extremely dark green. It does not emit sparks under the flint, and is perfectly fusible without the addition of any other material, provided it be exposed to an intense fire, and then it is converted into a black or greenish glass. It is somewhat harder than horn stone properly so called-* it much resembles basalt, and when broken, its fragments are rhoniboidal. PASTES. 163 The touchstone came formerly from Asia Minor ; now it is found in Bohemia, Silesia, and in Saxony. This stone may be considered as very useful in the arts, but not as a gem. Schistose silicates, jaspers, basalts, and black " breccie " can sometimes be used instead. Very ancient weapons have been found, made of this material. LXXY. PASTES. IMITATIONS of gems, of camei, and of engraved stones, as well as other ornaments made in glass, are, in Italy, always called paste. These imitations were also made by the ancients. In the Tyrrhenian tombs and on Egyptian mummies, necklaces of margherite are found, made of coloured glass. Besides the margherite and other feminine orna- ments, the Tyrrhenians made vases, cups, and balsamari, all of which were made in two different manners; some have a foundation of terra-cotta covered with a vitrification of generally-opaque colours; and these are found in the most ancient tombs. Others are of bright colours, transparent and opaque, and altogether in glass. Amulets, also, cups, balsamari, and globules of glass, often figured and interspersed with globules of gold finely worked, are found in the Etruscan tombs, and 164 , GEMS. bear witness to the high degree which this art had reached amongst this people in Italy. The Etruscans, however, used glass to imitate en- graved agates, which they set in seal rings. The Egyptians continued for many centuries this Tyrrhenian art, and sent out great quantities of terra- cotta ornaments covered with a vitrification, which was coloured either blue, greenish, or white. They are principally " margherite," little idols, amulets, and scarabaei of rough design ; and it is strange to remark that some, of very similar design, have been found in the Tyrrhenian tombs. In the days of Ptolemy the Egyptians made many elegant pieces of work, with very thin small sticks of varied-coloured glass, cemented together by a softer glass, almost always blue, the whole so disposed as to represent a given design. The Greeks and Romans also cultivated this art. Pliny often laments the difficulty experienced in Eome of discerning true, from imitation glass gems, and men- tions a sort of crystal "which was used in making cups (escaria vasa), another entirely dark red, called hcema- tinum, and others perfect imitations of agate, lapis-lazuli, and sapphires."* The Greco-Eomani fragments now found are of a thousand different kinds, and it would be tedious to describe them ; some of them resemble the modern glasses of Murano. In the third century, A.D., Egypt was already cele- brated above all countries for the manufacture of its * Nat. Hist, xxxvi. xxvi. 67. PASTES. 165 glass; and we know that Adrian sent to his friend Ser- vian, as a memento of his sojourn there, two precious glass cups (calices allasontes versicolores), which had been given him by the priest of the temple of Serapis, in Alexandria.* After the Antonines, the art of making glass continued to flourish in Rome. This is proved by the sacred vases found in the catacombs, where, on white and transpa- rent glass, we see figures and inscriptions in gold, all in the rough style of the period, i.e., from the fourth to the eighth century. | The dark barbarism of mediaeval times makes any research useless as to the arts in glass in the Middle Ages ; but the ornaments in engraved bronze, and in intaglio filled with enamel, also the stained glass in some sanctuaries, prove that it continued to the fifteenth century. At this period, the ancient tradition of this art having perhaps been preserved in Rome and Venice, we find that it already flourished there, engraved pastes being made there of every description, in imitation of gems and glass. Of this we have proof in the laboratory of Murano, where probably the identical method of the Tyrrhenians was preserved. In 1691, the Duke of Orleans, Regent of France, established a great laboratory of paste intagli in the Palais Royale at Paris, under the direction of the chemist Homberg. In this factory beautiful works * King, ' Antique Gems,' page 74. f Garucci, ' Vctri Omati.' 166 GEMS. were produced, which, from the originator, were called Orleans pastes. The art of imitating gems was much improved in the last century, by means of the discovery of new chemical components by a German named Strass, in compliment to whom all transparent glass, wrought into gems and used in imitation jewels, were called Strass stones. Towards the end of the eighteenth century there were public and private workshops in Eome, where imitation camei and glass intagli were made with such perfection as to render it difficult, if not impossible, for the most expert to distinguish the false from the true agate. Goethe relates, that he found the art so highly appre- ciated in Eome that strangers went there to practise it as amateurs. At present, Cades and Paoletti are the remaining representatives there of excellence in the art. The filograna glasses and Venetian enamels are pre- ferred to all made in any part of Europe. LXXVI. PERIDOT. THIS silicate of magnesia, coloured with oxide of iron, is of a dull olive-green colour. Being found generally enclosed in basalts and vol- PEEWOT. 1G7 canic sands, it acquired its name from the Greek TT/D<, around, and Sew, to bind, that is, bound round. The peridot has all the characteristics of a volcanic production, it differs from the chrysolite in colour and texture. It is composed of Silex 38 to 40 Magnesia .. .. 43 to 52 Oxide of iron . . . . 1 to 1 8 Its specific gravity is from 3 to 3*4. It possesses double refraction in a high degree, as its refractive power is 11. Although not very hard, it takes a very bright polish, which, however, diminishes in a short time. It is divided into Oriental and Western. It is found in pebbles in Ceylon, in Persia, Egypt, and Bohemia. In Greenland it is disseminated in the masses of magnetic iron, and between the large plates of mica, in the form of greenish or reddish grains. In the Azores it is not a defined crystal, although always transparent. The peridot is cut in the same manner as the emerald, and is sold by the carat at a very low price, unless it happens to be of extraordinary beauty. Very often sets of tormaline are brought from Ceylon and sold as peridots; but this fraud can be easily discovered by means of the magnetic property. The peridot was known to the ancients, but we do not know by what name. 108 GEMS. Now it is not much, valued ; nevertheless, in Italy, England, and Germany, it is used. Notwithstanding its rather soft . nature, it was, and is often, engraved. A great number are found in various tombs. In that belonging to the Orleans there was a cameo in peridot representing Cato. Crozat saw one on which was engraved a sibyl. The Abbe Pulini had in his collection a head of Medusa beautifully executed on a peridot, remarkable for clearness and good colour. LXXY1L PEARL. UNDER this name is understood in jewellery a con- cretion of carbonate of lime, round or tubercular, con- taining some organic substance. It has a light peculiar to itself, and therefore called pearly. It is generally of a milky- white colour, but is sometimes green, red, blue, and yellow. Its specific gravity is from 2 084; in consistency it equals all other calcareous substances, and, under the action of a diluted acid, it changes into a gelatinous substance, but only on the surface, the inner parts remaining intact. It is formed of various pellicles, one over the other, in a similar manner to the onion. The pearl is not a gem, but simply the production of a secretion of some bivalve shell. PEARL. 169 Different opinions are expressed by various authors as to the formation of this product. Some insist that it is an unfruitful ovum ; others, that it is a stone which covers a wound accidentally given by the animal to itself; others, lastly, suppose that the bivalve covers with an animal secretion some small extraneous body, which may have entered its shell by chance, and this it does perhaps that it may not be injured by its sharp edges. This opinion seems to us to be the most reason- able. We can assert as a fact that, when any pearl is sawn in two, various strata are seen to succeed each other, regularly, to the primitive nut which occupies the centre, and is of quite a different nature from the thin pearly layers. Feuchtwanger says that the Chinese string very small pearls on a thread, separating them with knots ; then they put them inside bivalves, which are taken at the suitable moment when they are open to enjoy the sun, placing them so that they do not touch the shell. They are afterwards put into the sea, but in an enclosed place, whence they are withdrawn after many years, when the pearls are found more or less enlarged, according to the time passed, and without those spots which in others are produced by adherence to the shell. It is thought that if a microscopic body of any form was put into a pearl oyster purposely, and that it could remain without adhering to the shell, it would serve as a nut for a pearl, which would retain its form externally. 170 GEMS. Bivalves in which pearls are found are of three kinds, and are called in scientific language meleagrina margaritifera, haliotis gigas, haliotis iris. There is another pearl, but of inferior quality, pro- cured from a shell which is known to mariners under the name of putellamola, or sea-ear. The most valued bivalve is the meleagrina margari- tifera, otherwise known as the pearl oyster. Pearl oysters inhabit both eastern and western seas, but always in warm latitudes. Inferior bivalves and the pearliferous turbinite are found in other seas, and in many rivers. Where the meleagrine are found collected in great quantities they are distinguished by the name of pearl banks. The most celebrated of these lie near the coasts of Ceylon, the Persian Gulf, near Japan, in the waters of Java and Sumatra, near the Isthmus of Panama, and at the mouths of the Eio la Hacha, in America. The ear-shells and bivalves which live in rivers are taken by hand ; but, on account of marine monsters, the fishing of meleagrine oysters is very dangerous, as they adhere to the deep submarine rocks. In the East pearl fishers before going out receive extreme unction from their priests ; and, on reaching the pearl bank, they murmur a prayer, throw them- selves into the sea, rake up oysters as long as they can remain under water, and then rise up to deposit their take in the boats. After a little rest, they return to their dangerous fishing. PEARL. 171 The daring Americans go to Panama to fish pearli- ferous bivalves in the depths of the ocean, rivalling each other in vigour and dexterity. The quiet Swede, while seated in his boat, seeks the meleagrine in the depths of his seas, and loosens them from the rocks with solid and long pincers of iron. The pearls which are brought by the fishers are called virgin pearls. The merchant classifies and divides them according to form, colour, and quality ; puts the round ones together, pairs those in form of a pear, takes away the irregular ones, which are called ~barocche, or out of the round, and puts the smallest ones aside. The round pearls are pierced and strung with a silken thread, and often with much art, to give a better effect, whilst the equality of colour and of size greatly influence their price. A perfect pearl ought to be without inequalities of surface. "Whatever its form, pure, of a silvery white colour, slightly blue or yellow, without roughness, and rather bright. In such condition pearls weighing 1 grain are worth 25 lire the pennyweight. 2 69 3 150 . 4 300 and so on ; the value increases according to the size ; but when they weigh more than two pennyweights they obtain fancy prices. 172 GEMS. The barocche pearls are rather valued in Spain and in Poland. The smallest are sold by the ounce. There are some which, on account of the singularity of their form, have been compared to different objects and figures. The goldsmith avails himself of this peculiarity by making art finish that which Nature has, so to say, merely sketched ; and, by means of the setting in gold, and the addition of other ornamental stones, brighter and better formed, making a desired figure. Caire saw in one pearl almost the head of a dog ; in another the golden fleece ; and in a third he thought he per- ceived the form of the famous torso of Belvidere. Amongst all feminine ornaments the pearl is that which is the most becoming to youth. Unlike all other gems, it cannot be beautified by the hand of man, who, in trying to improve it, spoils it. It is falsely affirmed by some that the yellow tint they acquire in the course of years by contact with the air can be counteracted, either by cooking them in bread, rubbing them with rice, boiled salad, or placing them for a short time in the gastric juice of a fowl recently killed. Italian jewels are often found set with pearls. In the New Testament they are mentioned. Twenty centuries ago they were used as ornaments in Greece. Theophrastus thought them equal to precious stones. Julius Caesar made a present to Servilia, mother of Brutus, of a pearl which had cost him a sum equal to one million two hundred thousand lire. 1\EAEL. 173 In one of Pompey's triumphs there were amongst the spoils of the conquered thirty-three crowns of pearl. Who has not heard of Cleopatra's pearls ? She, that with oriental splendour she might spend on one supper an amount of wealth which could not be calculated, took off the pearls she wore, and drank them in vinegar. So say the ancient authors, who would have us believe that pearls were dissolved into a gelatinous substance; but if this may be true of pearls infused in pure acetic acid, it is not possible if they are put into potable vine- gar, where they only decompose if left a very long time ; whence this tradition must be considered fabulous. The Romans, in the time of the Empire, thought so highly of pearls, that they reckoned them amongst their most precious articles to be transmitted legally to their heirs. Often in the sales sub asta they bid against each other for them, so much as to increase their price enor- mously. They possessed an inestimable quantity of these gems taken from subdued provinces, and, neverthe- less, had not sufficient to satisfy their magnificent ideas. The commerce with Arabia increased this inordinate luxury. The interior of the Temple of Venus in Eome was adorned with pearls, and the dress of the wealthy were ornamented with them all over, even to the shoes, which made Pliny exclaim, with bitter irony, " It is not sufficient for them to wear pearls, but they must trample and walk over them."* Alexander Severus in this respect showed com- * Nat. Hist. ix. xxxv. 53. 174 GEMS. mendable moderation ; for, having received a gift of two very large pearls, he desired that his wife should never wear them in public. After the fall of the Koman Colossus the barbarian invaders adorned themselves with pearls, and with them also ecclesiastical orna- ments were enriched. The Greeks of Byzantium made immoderate use of them ; and in this they were imitated by the inhabitants of the banks of the Danube, and by the Tartar successors of Eurik. At the period of the revival of the arts, the dis- covery of Columbus brought a great supply of them to Europe, whilst the East still continued to hold her own in great estimation. Eudolf II. of Austria exhibited a superb pearl, which weighed 180 grains. Philip II. of Spain had a pear-shaped pearl of the size of a pigeon's egg, weighing 134 grains. It was valued at 50,000 ducats, and was called ^eregrina^ or the in- comparable. However, they had not yet seen that which Gougitas, a merchant of Calais, brought from India to Philip IV., which was pear-shaped, and weighed 480 grains. It is said that this king asked the merchant, " How did you venture to risk such a fortune in acquiring so small an object ?" " Sire," answered the other, " because I knew there was a king in Spain who would buy it." Leo X. bought a pearl for 80,000 crowns. Tavernier describes one belonging to the King of Persia, which he states to have cost 1,600,000 lire. FALSE PEARLS. 175 Two Greek merchants at Moscow had one which weighed 27-J carats. It is said that the King of Portugal has one as large as a pear. In the votive crown dedicated by the Luke of Aosta to the Church of the Holy Sepulchre, and which was made by me, I put a pearl, which, similar to that sold by Gougitas to Philip IV., King of Spain, weighs about 480 grains. It is in the form of a pear, and hangs like a drop from the crown. LXXVIII. FALSE PEARLS. THE beauty of the pearl, which so much enhances female loveliness, creates the desire for exact imita- tions at much lower prices. Nevertheless, we do not know whether the ancients made false pearls or not. The French claim the invention of imitating pearls for one of their citizens, named Jacquin. We shall not dispute as to who is the author of this invention, but merely state that in Italy false pearls have been made for some centuries past, and by a method altogether different from that of the Paris bead- maker. It is said that Jacquin being one day at Passy, observed that those small fish which we call argentine, 176 GEMS. or silver fish, when washed in a sea-shell, left certain particles, which seenied to silver the surface. Seeing that they much resembled the brightness of the pearl, he thought of applying them, mixed with mucilage, inside some small balls of glass. Having succeeded, he gave the strange name of essence of the East to his production. The argentine is a very common, white little fish, which is found abundantly in the rivers of Italy, France, and Germany. In order to extract the essence of the East, they are washed, while tightly compressed, in a vase of very pure water. The result is a material of silvery colour which, when taken from the water, dried and compressed, is again immersed in another vase, and after a few days the liquid is decanted and the precipitate gathered with care. Eighteen thousand argentine yield five hundred grammes of essence of the East. In order to prevent the decomposition of this animal substance, they had recourse to various chemical ex- pedients, which for a long time remained secret to all but the inventors. Now, the most usual plan is to add ammoniacal liquid or volatile alkali to the decanted mass. The pearls of France in glass, and those of Eome in wax, are both made of the essence of the East ; but the process adopted in Eome differs very much from the French method, and perhaps is connected with a tradition more ancient than the invention of Jacquin. FALSE PEARLS. 177 For here the beadmakers are accustomed to make little globes of alabaster or Volterra chalk, which are then covered with very white virgin wax ; over this they afterwards spread the essence of the East, mixed with fish glue, by which means the extract of argentine remains fixed and bright on the round surface. The Venetian pearls are, instead, made of white glass fused into globules, within which they pour substances of various colours by means of particular processes, which, coming to us directly from the only city that preserved the tradition of ancient art, are perhaps those same which were used in the most remote an- tiquity. The Lemaire pearls are balls of glass covered with a kind of varnish, composed of 3 ounces of extract of pure argentine. J vellum. 1 white wax. 1 powdered alabaster. Many chemical compositions were proposed as sub- stitutes for these. Barbot advises the mixture of 1 ounce of bismuth, 2 corrosive sublimate, pounded separately, mixed and distilled twice. He asserts that this substance serves to imitate pearls, or to represent them in painting, with beautiful effect. 178 GEMS. LXXIX. PYROXENUM. THIS name is given to certain substances found by Haiiy, scattered in lava and in rocks of igneous origin, to which he thought them quite foreign, whence the name of 7r9p, fire, and eyos, stranger. For a long time they were confounded with the am- phibole, with which they have in common the form of the crystal and its components, but in different proportions. That which distinguishes the pyroxenum from the amphibole completely is its inferior brightness, its vitre- ous light, and, above all, its cleavage in three different planes parallel to the base. The colours of the pyroxenum are black, dark green, white, and grey. Its most common crystals are different prisms with oblique axes ; they are, however, sometimes met with in irregular octahedral prisms, more or less modified, and in pebbles either granular or of a dense substance. All these crystals are generally small ; their specific gravity is from 3-1 to 3-4, and their very variable con- formation yields on analysis Silex 48 to 52 Chalk .. .. 13 to 24 Alumina .. .. 3 to 5 Magnesia .. .. 8 to 10 Oxide of iron . . 1 2 to 14 Oxide of manganese . . 1 to 2 PYEOXENUM. 179 The basalt pyroxenum is of a better and brighter green than that found in lava. It easily marks glass and is translucent ; it has unequal breakage and very easy cleavage. Those found on Etna are of a bright greenish black, having a concave though imperfect breakage. \Ve cannot declare to a certainty whether crystals of pyroxenum existed previous to volcanic eruptions, or if they crystallized afterwards, but the first hypothesis seems the most likely. Some black varieties of pyro- xenum are known by the name of augite ; their dust is brown, and they took this name on account of their brightness, from the Greek avy-rj, splendour. Certain green pyroxenum crystals from the Tyrol, more or less modified irregular octahedrons, received the name of fassaiti, because they are found in the valley of Fassa. The salilite pyroxenum, formed in crystals, is green and variegated. The pyroxenum diopsido, much more rare, and found in transparent crystals of a grey-green and sometimes white, contains only lime, magnesia, and a small quantity of protoxide of iron ; the double refraction which its cleavage gives caused Haiiy to give it the name it bears of &uo, two, ot/as, sight, that is, double mew, or mineral which has two distinct characters ; it bears the name of alalite on account of its being found crystallized in the valley of Ala, near Turin ; it is dug up in lamina, in the valley of Mussa, in the same province, and thence called mussite. 180 GEMS. The pyroxenum Jiederibergite, from the name of the chemist Hedenburg, is dark -green and almost black ; it only contains protoxide of iron, to which there is sometimes united a quantity of magnesia. In general, pyroxenum of every quality is but little used, although well adapted for jewellery, in making ornaments for mourning. LXXX. PISOLITE. THIS stone, which is commonly called pisinella stone, differs from the oolite, to which it is related, in the larger dimensions of the aggregated particles, which, in it, are composed of concentric leaves. Like the oolite, it is composed of small spheres united by a calcareous cement, and it is found of different colours reddish, brown, yellowish, and white. It looks well when cut and polished. It is found in the alluvial deposits of the warm waters, rising at Carlsbad, in Bohemia, and at the baths of San Filippo, in Tuscany. Its name is derived from TTIO-OS, pease, , stone, on account of its most common colour. PLASMA. 181 % LXXXI. PLASMA. UNDER this name many people understand two differ- ent stones, thinking that the ancients confounded them together and called them prasius. But I think that the prasina, or prasius of antiquity, is not the stone which, with more propriety, we now call plasma ; moreover, it appears to me they ought to be accurately distinguished. I shall speak here of the plasma, and afterwards of the prasina, showing how this is not a variety of the plasma, and the ancients did not confound them, as it is said, one with the other, but that they indicated the plasma by a different name from the prasius, and perhaps by that of molochites. The plasma is a semi-transparent agate, coloured green by some metallic oxide, probably copper or nickel; although often in the purest quality it ap- proaches the colour of a fine emerald, yet it never possesses its brightne-s, is never pure, but always marked with little black and yellow spots. Like the calcedony, it scratches glass deeply, and its specific gravity is from 2'58 to 2'66. In colour it is dark olive, resinous, and semi-trans- parent. The extreme fineness of its texture renders it suitable for engraving. It is found in the East and in the Black Forest. As we do not know exactly what name the ancients 182 G-EM8. gave it we cannot know where they procured it, but fine pieces, both rough and worked, are often found amongst the remains of Italian monuments. It appears 'that the plasma was only used orna- mentally during the time of the Lower Roman Empire, as the subjects of the ancient intagli and the quality of the execution bear witness. Contrary to my opinion, to which for the above mentioned reasons I firmly adhere, Emmanuel asserts that even the Greeks called this stone plasma, because its name was derived from the word TrA-aayxa, image; and Barbot, misled by the same ambiguity, says that the plasma comes only from India, and that in ancient times it was probably thence brought to wealthy Carthage, and from there to Rome. LXXXII. PORPHYRY. ALTHOUGH porphyry is not a gem, we think it right to make some mention of it, as we did of marble, as much for the purpose of following the example of those who have written on the subject of gems as because many works of art have been executed in that material - Porphyry is composed of a felspar rock called, scien- tifically, l&ptinite, mixed with crystals of ortosa and albite. The different kinds are distinguished by their ground colour, in red, green, white, brown, or black. Their specific gravity varies, according to their aggregated substance, from 2'69 to I'll. PORPHYRY. 183 The variety of porphyry most prized for its beauty, its urichangeableness, the beautiful polish it takes, for hardness and close texture, is that which was most generally adopted by the ancients, and is called antique porphyry. This variety is inclined to red or purple, whence the generic name of this stone, from the Greek Tropvpa, which signifies purple. Red porphyry, originally from Arabia, was subse- quently found in Sweden and Saxony, where it is procured of a dark colour, and sometimes blackish, mixed with grains of white. Black porphyry is that stone which the ancients called ophite, which is the same as serpentine. The figured porphyry of Egypt, which must not be confounded with the figured marble, is most valued when it has numerous yellow marks on a white ground. That kind with a dark red ground is more common. The green porphyry of Siberia, also found in Alvernia. shows spots or whitish grains on a greenish ground. The green porphyry of antiquity is now very rare : it is known by its long white square marks, which are in the form of St. Andrew's cross. Italy, France, and some other countries in Europe now yield us porphyry, some of which rivals the ancient stones in hardness and beauty, but the greater part are very inferior to them. Italian porphyry, especially, is almost all very hard and scaly; the variety of a light green, on a very dark green ground, is so common that it is used in Turin to pave the streets. The Romans and Greeks prized highly and used 184 GEMS. largely red, green, and black porphyries, which they procured from Egypt and Arabia, and many of their sarcophagi, statues, busts, and columns composed of this stone, now adorn our museums. Antique porphyries were often of considerable dimen- sions, and in proof of this we see the obelisk of Sixtus V. and the splendid columns of the church of St. Sophia of Constantinople. In the seventeenth century porphyry was still used all over Italy. At present porphyries are found in various regions of Europe, but, on account of their hardness, they are only used in works of art, or for utensils, as mortars, palettes, and stones for grinding colours. In 1823 two Englishmen, named Burton and 'Uil- kinson, discovered the great caverns which supplied porphyry to the ancients, and which are situated in. a group of mountains, about twenty-five miles from the Red Sea, and called Djebel Dokhan. LXXXIII. PRASE. PRASE is a diaphanous mineral, semi-transparent, and not very hard, and on account of its colour is called prase, or prasina, from the Greek Trpacrov, leek, because it is green as the leaves of the onion. PEASE. 185 It takes a polish which would be perfect if it was not resinous, and which it loses in the course of time. Its colour, quite different from that of the plasma, which is rather olive, is of a decidedly emerald green. Small and rare are the pieces of pure prase, as this stone is always mixed and marked with lime, and its internal crystallization is not homogeneous or perfect. When it presents the appearance of a regular crystal it takes the form of a prism or pyramid, having six faces of medium size ; its external surface is rough and not very bright, but the breakage is scaly, concave, and of a vitreous light. The prase in block is often formed of pieces stuck together, whose faces, somewhat rough, are obliquely lined. This mineral, which has a specific gravity of 2-67, yields on being analysed Silex 92-5 Alumina .. .. .. 0*5 Glucine .. .. .. 4' 5 Magnesia . . . . . . 1 ' Oxide of iron .. .. 0'5 Oxide of nickel . . . . 1 ' The ancients believed prase to be a kind of imperfect emerald, and besides the name of prasium, they also called it smamgdoprasium ; but no one has left an exact description of it ; and Theophrastus, who suc- ceeded Aristotle, made greater confusion by giving the name of smaragdus to every kind of green stone. This 186 G.EM8. confusion was perpetuated by rendering the Greco- Latino name of the stone common, and it was called, indifferently, prasma, plasma, or the matrix of the emerald. I have explained above which is the stone that properly claims the name of plasma ; that which I call prase (or prasina) is now acknowledged to be the matrix of the emerald : this can be proved by observ- ing how the pieces anciently used, of this substance, are identical with the prase which was taken from the emeraldiferous mines of America. Prase is still found in Saxony, Bohemia, Finland, Scotland, and Siberia. The brittleness of the prase prevents it being en- graved. I have seen an immense number of ancient pierced " margherite " in prase, but I never saw any pieces engraved. I tried to cut some, but they broke under the trial. LXXXIV. QUIRITINE. BY this name Ceselli denoted a mineral composed of silex, alumina, soda, lime, protoxide of iron, and traces of magnesia ; it was found by him on Mount Lazuli in 1856. RUBELLITE. 187 LXXXV. RUBELLITE. THIS mineral, but little known, is so called from rubeus, which signifies red, and Ai#os, a stone. It is however called sibarite, because found chiefly in Siberia. The rubellite has all the properties of the tourmaline, and its colour varies from hyacinth to pink ; sometimes, when shaded from the light, it seems blue. The rubellite is found in the United States of America as well as in Siberia. Feuchtwangcr speaks of one of these stones found there whose form is a perfect prism, dark red on one side, and dark green on the other; it was found in 1850, and exhibited at New York in 1853. Such stones are also found at Chesterfield, in Massa- chusetts. The Siberian rubellite cuts smooth and has often a milky- white iridized light. When transparent it is quite clear, acquires a beautiful polish, and may be called rather a valuable gem. A rubellite, when pure and of a perfect colour, may be worth as much as 7,000 lire. Those found in Maine are rare. It has been thought by some that the rubellite is the ly 11 curium of the ancients, but their properties are not similar. We have rubellites which are certainly antique, but none of them are found engraved. 188 GEMS. LXXXYL RUBY. BY this name, which comes from the appellative of rubeus, on account of their colour, three gems are known, very different in their constitution, but re- sembling each other in colour so as often to be con- founded together; they are the red corundum or Oriental ruby, the red spinel, and the balais. We shall treat of them separately. 1. ORIENTAL RUBY. The gem most prized next to the diamond is the ruby, or red corundum of the naturalists. The splendour of its tints, sometimes purely red, at other times violet, pink, or purple, makes it the most beautiful coloured gem in nature. The hardness of the Oriental ruby is immediately second to that of the diamond, and it is superior to that of the other corundums. It has double refraction, although not of a high degree ; its light is vitreous ; it bears the strongest fire without losing colour or form, but by means of a special solvent it is transformed with difficulty into a clear glass. It is easily perceived from its crystals that it has experienced the action of fire, but, notwithstanding, they are capable of cleavage. Their form is not well defined, generally oval and imperfect, but still oc- tagonal or round, or flattened at one part. RUBY. 189 The specific gravity of the Oriental ruby, greater than that of all other gems, is from 8-900 to 4-2833. When analysed it yields Alumina .. .. .. 98 '5 Oxide of iron . . . . 1 Remainder .. .. 0'5 When rubbed it becomes electric, and remains so for a considerable time. The best Oriental rubies come from China and India. They are found in the island of Ceylon, in the moun- tains of Capelan, in Pegu, ten days' journey from Syrian, at Carnbaja, and at Lahore. Those from China are procured in the mountains of the province of Ya-nan. The mines of Burmah, which produce the best, have been known for many centuries. Being a government monopoly, they are rigorously guarded, and no European can even see them. It is said that the king of that country possesses some of the most beautiful, and he numbers amongst his titles that of Lord of the Rubies. When the superintendent in those mines sends notice to the Court of the discovery of an extraordinary gem, the king orders an immense and sumptuous procession of soldiers, lords, and elephants to go and take it. The rubies of Ceylon, which are those most prized, are gathered on the shore of a river which flows to Sittivacca. The red corundums of Australia, hitherto found, are of a bad quality. None have yet been found in America. 190 GEMS. An Oriental ruby may be considered fine when neither too light nor too dark, but precisely of that colour which we call pigeon's blood. It is cut on a wheel covered with diamond dust. Emmanuel asserts that rubies of the finest colour, of less than one carat in weight, are worth from 50 to 200 lire the carat; that those weighing upwards of four carats have no determined price, and for the others he gives the following table : 1 carat from 350 to 500 lire. If 625 to 900 2 1,750 to 2,000 3 5,000 to 6,25^ ., 4 10,000 to 11,500 He adds, that pale, blackish, violet, and split rubies are common, and of little value. Those which are red asterias are prized on account of their rarity. The ancients gave many names to this beautiful gem. Marbodio called it granaticus, from its colour being similar to that of the pomegranate. Marbodius named it Antrax, which signifies burning carbon, because of the vivid rays it emits when struck by the sun. In describing it, he asserts that a very small gem of this kind was sold for a sum equivalent to one thousand lire. Pliny describes them by the name of carbuncle, or " carbunculi a similitudine ignis appellati" Amongst the many varieties, he places carbunculi RUBY. 191 acausti and apiroti " cum ipsi non sentiant ignes" which properties perfectly suit the red corundum. He, according to the ancient custom, divides the masculine, which is bright and resplendent, from the feminine, which is pale and less bright : " Fcemince languidius refulgentes" It is said that preference is given to the Indian rubies, amongst which those are retained as best which, from the extreme vivacity of red, incline to amethystine violet : " optimiores .... quorum exfremus ig- niculus in ametysti violam exeat." As these are the finest now seen, they are denominated ametliyslizonti. In the second rank as to value, they place the " sirtiti pinnato fulgore radiantes" and give the name of lifhyzonihi to the dark, pale, and discoloured Indian stones. We conclude that it is most difficult to distinguish the different kind of carbuncles when set, as it is still usual, at the present time, to modify the tint, by placing under it a coloured substance, which can impart bright- ness and beauty to a gem naturally pale 'and dull : " nee est aliud difficilius quam discernere Jicec genera, tanta est in eis occasio artis subditis per quce translucere cogantur" As in the case of other gems, the ancients used to make even false rubies in red glass. King says, he saw one beautifully engraved with a head of Medusa, so well imitated that he could not at first declaie whether it was gem or glass; even the flaws of an imperfect gem were imitated in it ; and Pliny asserts 192 GEMS. that, in his time, carbuncles were made of glass so like the real that it was only possible to know the differ- ence by the hardness. In some ancient jewels, as in Eastern ornaments, rubies are seen very roughly worked, but well poli>hed and pierced from side to side, with grave injury to the beauty of the gem. In the Hertz collection there was a necklace com- posed of rubies and rough emeralds of excellent quality and colour, and of the size of small beans, pierced and strongly fastened together with a golden thread. I have never yet seen Oriental rubies engraved which could with certainty be called antique. I have tried manj 1 - times to have some engraved, but, in spite of the best efforts of skilled artificers, the results were but mediocre. Wherefore, Lessing, a scientific German, and the Count de Clarac, a French archa3ologian, having, as the result of their long experience, declared as gene- rally modern all the intagli on corundums which were asserted by others to be antique, I adhere to their authoritative opinion with regard to the Oriental ruby. 2. SPINEL RUBY. The spinel is an anhydrous aluminate, having a base of magnesia, zinc, and iron, crystallized in regular octahedrons differently modified, and sometimes in tetrahedrons. In general, the planes of its crystal are more regular RUBY. 193 than those of the corundum, from which it differs in its composition only by having a lesser quantity of alumina. It has single refraction like the diamond. It marks quartz, but is marked by the corundum. It acquires electricity by friction ; does not melt under the action of the blow-pipe, and in contact with acids does not alter in the least. Its specific gravity is 3*7 ; its hardness, 7*56. It is coloured by chromic acid. The spinel is always found with the corundum, and it appears that both are produced by the same cause. The spinel is of various colours ; and in that section of the mirieralogical cabinet of the Eoman university where the collection of the illustrious Conte Lavinio Spada Medici is arranged above fifty different kinds of spinelle, belonging to this eminent cultivator of mineralogical science, are to be seen ; there are some perfectly white and clear, reddish- white, pale rose, and passing through all shades of wine-red till they reach blackish-red. They are found in violet of every gradation of tint. In Greenland and at Vesuvius they are found of amethyst colour. At Aker, in Sweden, as also at Straskan, in Moravia, are found spinels of a blue colour, but not transparent. The ferriferous spinel, Cingalese, or black spinel, a variety which is very small, bright, and black, is found in the lava of the Somma, in the lands of Val o 194: GEMS. di Fassa, in the Tyrol, in Bohemia, in the island of Ceylon, and in many parts of South America ; and are called pleonasto, from the Greek, which means very abundant. The zinciferous spinel, also called automalite or gahnite, is an alumina of greenish or greyish zinc, generally opaque. Up to the present time it has only been found in Switzerland, and near the city of Franklin, in South America. White spinel is procured from Mount Laziali. Berzelins asserts that when the spinel is heated, it first takes a dark tint, then becomes black, after- wards opaque, but on cooling it changes colour and. becomes of a limpid green, from which it gradually returns to its natural colour. The finest of the spinels is that which bears the additional name of ruby, because red ; it is like the Oriental ruby, although its lively tint tends a little 'to yellow, yet not so much as the jacinth and garnet. Its chemical composition is Alumina .. .. 69-01 Magnesia .. .. 26-21 Protoxide of iron .. 0*71 Oxide of chrome . . 1 10 Silex 2-02 The other varieties differ in the proportion of their component parts ; and in some by the mixture of other substances. Many spinel rubies are fraudulently sold as Oriental ItUBY. 193 rubies, but the deceit is easily discovered by the differ- ing hardness and the specific gravity. We do not know the name by which the ancients indicated the different varieties of spinel ; only, in my opinion, it may be asserted that the red or ruby spinel was described by Pliny under the name of alabandic carbuncle, carbunculus alabandicus, because, in speaking of carbuncles in general, he affirms, " Alaban- dicos cseteris nigriores esse ;" that is, to ' have a darker colour, and this is the case with the spinel ruby. It is said to be procured in Ortosia, and cut in Alabanda, whence the name given to them. 3. BALAIS RUBY. By balais is meant a ruby of a lighter colour than the spinel, rather tending to pink, and whose specific gravity is never more than 3*446. It is even less hard than the spinel ruby, and contains a greater quantity of magnesia. The balais is more easily scratched by the emerald than the emerald is by the rock-crystal. It will take a beautiful polish, but only as the result of much patience, and the use of a special chemical composition . on the wheel when being worked. Caire is convinced that in India they have, for this purpose, a secret specific, as balais are brought thence scarcely out of the original form, yet having a beautiful artificial light. Neither balais nor spinels have ever been seen having the qualities of the asteria. 196 GEMS. The balais is often found in large crystals ; and if that is true which we read in the history of the Grecian empire in the dark ages, there were seen some of enor- mous dimensions ; and one of the Cantacuzeni, em- peror of Constantinople, had given ten balais rubies, weighing each eight ounces, to the Venetians, in the year 1343. Pliny says that, amongst burning stones, the chalce- dony and lichnite alone were found large enough to permit of their being made into cups; and in describing the lichnite he thus expresses himself : "Of the same species is the lichnite, so called because it shines brightly by lamp-light. It is procured in the neigh- bourhood of Ortosia, and all over Caria and its vicinity; but the most beautiful comes from India, and it is said by some to be a carbuncle of minor brightness. When warmed in the sun, or rubbed between the fingers, it attracts straws." From this description, King concludes that the lichnite is an Oriental ruby ; and in confirmation of his opinion, he repeats a passage of Solinus, who says the lichnite is thus called because it shines much by lamp-light, is transparent, very bright, attracts straws when warmed in the sun, or rubbed ; is not easily cut, and is of no use for seals, as it repels wax as if bitten by it : velut quodam animalis morsu. However, it seems to me that this description, and also that of Pliny, agree in general more with the balais than with the corundum. It is true that the balais and spinel can be very RUBY. 197 well engraved by the tool, but how could this have been done by the ancients? Besides, did they ever find clear corundums of sufficient size to make cups? " Potoria vasa ct ex hoc lapide et ex licknite factitata invenio." Therefore, I believe the lichnite to be rather our balais than the Oriental ruby. In the dark ages this name was given it through the Greek rendering of Balassus, or Palassus, because it was supposed to be the bark or house in which the true ruby resided; and Andrea Braccio says, explicitly, that " The name of balais comes from the word palatium, because it is supposed to be the matrix or palace in which the ruby is found." Emmanuel believes, on the contrary, that this name had its origin from the province of Asia now called Beloochistan, and anciently Badakschan or Balaschan. Emmanuel makes the same observation as Sebaldo Savio : " Nomen ejus belashsch diciturque a Teifaschio adduci ex BalashcJiane, quam regionem barbari Badachschan vacant, cstque secundum eum pars terra? Turcarum quce ad Tartarmm vergit." And he goes on to assert that even at the present day this gem is called Badakschiani, in Persia. A Persian tradition holds that the balais remained unknown until the occurrence of an earthquake, which, by dividing the mountain in which it had been concealed, discovered and oifered it to human rapacity. Marco Polo, in the description of his voyages, tells 198 GEMS. us that this gem is found principally in certain mountains called SheJcinim. One of the finest balais known was in possession of the King of Oude. On it was engraved the name of one Julal-u-din, and from this it took the name at court of Lal-i-ja 1 adi. It was the size of a walnut, and very brilliant. In the middle ages it was thought that the balais and the red corundum had certain occult and super- natural virtues. Eliano relates how a stork, having broken a leg, was cured by an old woman named Eraclide; he afterwards flew away, and returning, placed in her bosom a very fine balais which he carried in his bill, and gave to her as a token of gratitude. The balais is easily cut on the wheel, as already re- marked ; and I have seen many of them engraved, but none that I could, with certainty, say were of antique workmanship. LXXXVII. SARD. SARD is that stone which is generally called sardonica, to distinguish it from sard-onyx, of which we shall speak presently. The sard, then, calling it by the name bestowed on it by the Eomans, is an agate- quartz of a dark colour, between red and yellow. Consisting of the same components as the carnelian, it only differs from it in colour and fineness of texture. SARD. 199 Its specific gravity is equal to 2-603. When looked at against the light it is transparent, and appears more yellow than red; otherwise, its colour is more that of dark marone. Nevertheless, it is found of varied tints, from blackish-red to light chesnut. The beauty of the sard as used for engraving con- sists in the purity and evenness of colour, when looked at through the light. When a sard is very hard, it takes the name of Oriental sard, in accordance with the term applied to the most precious stones. This agate is brought from India, Arabia, Egypt and Armenia. Bohemia and Silesia also yield us sards, but they are much inferior. Engravers despise them on account of their smoke-coloured tint, sprinkled with bluish spots. In substance the sard appears to resemble the plasma very much, excepting in the colour. Scipio Africanus is the first of whom it is related that he continually wore a sard ring on his finger : this is told us by Demostrato. The origin of its name is disputed. Pliny believes it to be that this stone was originally found near Sardis, chief city of Lydia. He says, however, that very beautiful sards are found on the mountains of Maranai, near Babylon, and on the confines of Egypt. Others think that this name is derived from Sardinia ; but Cesio and St. Epiphanius maintain that it is 200 GEMS. called sard on account of its colour, which much re- sembles that of the flesh which adheres to the back- bone of the dried and salted sardine. The sard was, and is, much used in works of art, or in engravings. The most celebrated engravers prefer the quality called $andy, which is of a beautiful colour, but sprinkled with small opaque spots of a darker shade. At the present day it has become precious from its rarity. The most beautiful intagli known on sard are, Mars and Venus surprised by the gods, a group of nine figures, attributed to Yincenzo Belli, of Vicenza, and which belonged to the Orleans collection ; and the nuptials of Cupid and Psyche, cut by Trifone, and mentioned by Stosch, who saw this engraved gem in London. LXXXYIII. SAKD-AGATE. Tins is a sard which has an upper stratum of white agate, and is perfectly similar to the onyx in appear- ance. Caire and other authors thought they could substi- tute for the ancient name that of agate carnelian ; but it does not exactly express the nature of the stone, and therefore the other remains. The finest specimens have one stratum in sard and the other in white agate. The scarceness of the best kind makes them valuable. SARDONYX. 201 In this well-known stone there is a cameo belonging to the Genevosio collection, of Turin, which represents the Medicean Venus ; it is as large as the stones generally worn in rings, and the artist had the clever- ness to cut it on the reverse side ; thus, on the white crystalline ground of the agate, he has admirably raised the form of the goddess of Love, in sard, which from its colour has a very beautiful effect. LXXXIX. SARDONYX. THE ancients called this stone sar da-onyx. In this beautiful quartz are found, mixed in strata, the sub- stances of the sard properly so called, and of some, or many kinds of agate ; that is to say, of the chalcedony, jasper, carnelian, and such like; from this arises an enormous variety of colours, which, being mostly arranged in zones or regular lines, allow the artist to make the finest and most valued camei in sard- onyx. One of these stones, even without being cut, may be worth as much as two thousand lire, a price to which neither the sard or sard-agate ever reaches ; it differs from this last by the multiplicity of strata, or, when it has but two, by the opacity of the upper one. The most remarkable cameo now existing in sardonyx is in the Vienna cabinet ; it is attributed to Dioscoride. 202 GEMS. Although composed of but two strata, of which the one that forms the ground is of the finest sard, while the other, which is the relievo, is chalcedony, it may be said to be, if not the finest, at least amongst the most rare of the true antiques which have great artistic merit. It is 187m. long and 0-217 wide. It belonged to Philip the Fair, King of France, who gave it as a gift to the monastery of Poissy, whence it was stolen, during the religious wars that devastated France in the last cen- tury, and taken to Germany ; Eodolph II. there pur- chased it for the sum of 12,000 gold ducats, and placed it in the imperial cabinet. It represents, with twenty figures, the apotheosis of the Emperor Augustus. xc. EMERALD. THIS is a splendid and transparent gem, of a green colour, from the lightest to the darkest shade. It appears that its name has the same root in many languages; as in Arab it is zamarut; in Chaldaic, isma- ragdon ; in Greek, smaragdos ; in Latin, smaragdus ; in Spanish, esmeraldo ; and in French, emeraude. It is said to be derived from the Sanscrit smarakato, which means green ; or from the Greek word d/^apuo-crw, to shine or lighten. The emerald, like other gems, is divided into Oriental and Western. The most rare Oriental emerald is nothing but a clear green corundum. EMERALD. 203 This variety of corundum is very remarkable in being softer than the red and blue stones, and it would seem that the glucine which enters into its composition is the cause. It crystallizes in regular prisms having six faces, be- sides which may be seen various truncations ; its cleav- age is straight and quadruple, which property makes it easily distinguishable from other emeralds which have no cleavage. All Oriental emeralds have not the same degree of hardness ; their specific gravity, although it may differ from that of other corundums, yet in the hardest varieties often amounts to 3-01. The perfect corundum is of an herbaceous green, more or less dark, which by its silken light reposes and renews the sight. When analysed, it generally yields Silex 64-05 Alumina .. .. 15 '00 Glucine 13-00 Oxide of chrome . . 8*25 Lime 1-06 Water 2-00 Sometimes it gives in the residue a little oxide of iron. There were caverns of it in the island of Ceylon, at a place called Matoiila, but now they seem exhausted; even there they were seldom found in large crystals. This gem, when perfect and weighing more than two carats, is as valuable as the diamond. 204 GEMS. Between the emerald corundum and the Western emerald of fine quality there is the same difference as between the perfect red corundum and the perfect spinel. The Western emerald is a silicate of alumina, almost identical in its composition with the "beryl or aqua- marine. It is the least hard amongst gems, and therefore breaks easily. It crystallizes in truncated hexagonal prisms at the two extremities ; its crystals lie between the com- posite rocks and argillaceous schists, and also in the accidental cavities which occur in granite blocks. Sometimes it is found united with crystals of quartz, mica, and felspar. It is, moreover, procured from sul- phuretted iron, in carbonate of lime, and in sulphu- retted lime. This emerald has a vitreous and seldom a resinous light. It is soft when just taken from the mine, but hardens in the open air. Its specific gravity is between 2'73 and 2-76. Its hardness between 7 '05 and 8. It yields a white powder. It becomes electric by friction. It melts under the action of the blow-pipe, forming a limpid vesiculated glass of the consistency of borax. When calcined and still hot, if thrown into water, it breaks into fragments of various colours. It gives, on analysis, EMERALD. 205 Silex 68-50 Alumina .. .. 15 '75 Glucine .. .. .. 12 '50 Protoxide of iron . . 1 00 Earth 0-25 Oxide of chrome . . 30 Magnesia .. .. Traces. Soda .. .. .. Traces. It is not corroded by acids, but is soluble in salts of phosphorus. It is found in micaceous schists at Salz- burg, in the mountains of Sahara, in the argillaceous earths of Peru and of Siberia, at Henbachthal, in Ger- many, at the height of 8,700 feet above the level of the sea. The Western emerald is now procured principally from America, where the mines of Muzo, in Xew Gra- nada, are celebrated. Emeralds of very good quality are dug up at Odont- chelong, in Siberia, and at Ava, in India. This gem has often imperfections and flaws inside which quite deprive it of its lustre ; there are some, too, very opaque. It has been thought that the green colour of the emerald is derived from oxide of chrome ; but Levy, in the analysis, perceiving such a small quantity of chromic acid, formed the opinion that it was produced by some organic substance, which he imagined was a carburet of hydrogen similar to the chlorophyll which colours the leaves of plants. 206 GEMS. A great number of emeralds are seen in the precious ornaments of every age, as often in their natural crys- talline forms, simply pierced, as cut in different shapes. But under the name of smaragdus, all green stones are generally understood ; and so, the emerald, jade, jasper, malachite, plasma and prasina were confused together, and about twelve varieties of smaragdus were thus described. Theophrastus, in describing the emerald, distin- guishes it, nevertheless, from jasper and from other stones of minor value. " The emerald " (he says) " pos- sesses some particular virtues ; it imparts its colour to water when dipped in it. It also rests the eyes." After him, Pliny wrote : " The third place is given to emeralds, for many reasons. There is no colour which gives more pleasure to the sight than this ; for we view leaves and grass with delight, but emeralds with so much more, as nothing, however green, can be com- pared with them in intensity of colour. Besides this, they are the only gems that fill the eye, without fatiguing it ; and, moreover, when the sight is wearied, the emerald restores and relieves it; and for gem- engravers no other means of refreshing the eye is so agreeable as its beautiful green colour. Those of Scythia are the best none are harder or with less defect (nullis major austeritas aut minus vitii). And in the same proportion that emeralds differ from other gems, the Scythian differ from other emeralds. . . . After the Scythian, come those from Bactriana. The Egyptian stones hold the third rank, and are found at EMERALD. 207 Coptos, a city of the Thebai'd. Other kinds are found in copper mines." After all that has been said, it appears to me that we should not hold as truth the statements of many old authors, and among them Taveinier, who assert that the ancients had no knowledge of the emerald, and that it was first brought by the Spaniards from Ameiica to Asia and Europe, in times not very remote from ours. The Greeks and Eomans then had their precious emeralds from India, Bactriana and Eg} T pt. In Upper Egypt there is a chain of mountains, not- far from the city of Asna, where there are some places still called the mines of emerald. By order of the Viceroy, the French traveller Cailloud explored those places and found there some old mines ; there were houses and tools abandoned, in all probability, in the second century A.D. Wilkinson afterwards discovered extensive caverns, also, on Mount Zahara, and there picked up emeralds similar to the ancient Greek and Kornan gems, that is, inferior to those from America and India. The emerald continued to be used in precious orna- ments even in the darkest times of barbarism. The iron crown which Theolinda gave in the sixth century to the cathedral of Mouza had many emeralds mixed with its rubies and sapphires. There were some in the crown of Agilulfo, restored by the celebiated Anguillotto Braccioforte in the fourteenth century, and therefore many years before the birth of Columbus. There were emeralds in the cross of Lothairius, a 208 GEMS. work of the ninth century, and in the celebrated crown of St. Stephen of Hungary, made in the tenth. There was a very fine emerald in the tiara of Julius II., who died in 1513, thirty-two years before the discovery of Peru. And, finally, Benvenuto Cellini, when speaking of the antique gems which he bought from the country-people of Eome, describes an emerald with an engraving, said to be antique, representing the head of a horse. The discovery of America really furnished all Europe with a great quantity of those gems which of all the Western stones are the most beautiful. When Pizarro conquered Peru, he went as far as Cal- camalca, a considerable city, whose chief offered him many gold and silver vases, with a quantity of large emeralds, which had probably been obtained from the mines of Warta. But this did not satisfy the cupi- dity of the invaders, who forcibly took the treasures which for ages had been accumulating in the principal temple of that empire. Amongst the rest, they got a great number of these gems, as the priests persuaded the people that the goddess Esmeralda, to whom the temple was dedicated, dwelt in an emerald the size of an ostrich egg, and that no offering was more accept- able to her than these stones. The price of emeralds is very variable, depending on the size, colour and clearness. A very pure and perfect Oriental emerald, of six carats, may be worth 10,000 lire ; and there are some of more than fifty carats, which are not worth more EMERALD. 209 than 10 lire the carat. It is believed that in the trea- sury of Loreto there is still a quantity of emerald crystals, which being naturally united together, are of the size of a human head. They were dedicated there to the Virgin, by the miners of Peru, represented by the Marquis of A'ragon, then ambassador from Spain to Rome. It is said that in the imperial treasury of Vienna there is an emerald which weighs 2,205 carats and is valued at 300,000 gold crowns. In a work entitled * Memoires du Regne de Catherine II.,' it is asserted that there is an emerald belonging to the Russian crown as large as a hen's egg. The finest emerald known is in the imperial cabinet of St. Petersburg ; it weighs 30 carats ; its colour and clearness are perfect. I saw, with the Count Lavinio Spada, a natural emerald which came from Peru ; it was of a beautiful colour, and was ten centimetres long and about five wide. It is said that Dhuleep Singh has a very perfect emerald about five centimetres long, three in width, and two in height. The Duke of Devonshire has one which weighs nine ounces. Beautiful engravings on emerald are made, notwith- standing the fragility of the material. Ismenia, an ancient Italian musician, is said to have ha'd one repre- senting Amimone, daughter of Diana ; Gorlee, of An- twerp, published the illustration of a large oval emerald 210 GEMS. on which is represented, with three figures, the soul carried away by pleasures. The ancients dedicated , this gem to Mercury, and believed that it had the peculiar virtue of preserving the sight if worn in a ring, of alleviating the pains of parturition, and of being an infallible talisman for preserving chastity. AVhen reduced to powder, six grains of it were swallowed as a noble remedy for various maladies. According to Ebelman, Western emeralds could be manufactured by melting a mixture of Silex 7-00 Alumina .. .. 1*60 Glucine 1-40 Boracic acid, fused .. 4 '06 Oxide of chrome . . 10 From this results a green crystal, having a specific gravity of 2*73 to 2-77, which can be marked by an English file, but deeply marks common white crystal and the softer kinds of quartz. XCI. EMERY. MINERAL substance whose name is derived from a wo'rd by which the Greeks meant the stone used by lapidaries in cutting gems. . It is divided, like those, into Oriental and Western. EMEEY. 211 Oriental emery is nothing but granular corundum, that is, an aluminate whose specific gravity is 4, and which, when analysed, yields Alumina .. .. ..86 Silex 3 Iron .. .. .. 4 Waste 7 By some it is called adamantine spar, and is found in China, Bengal, and Ceylon in large octahedrons, which, under a given angle of luminous rays, reflect bluish light, but are generally opaque. The best comes from China, and contains more oxidized iron than that from Bengal. When pulverised, it scratches some gems, but not the diamond. The Western granular corundum, or Western emery, is rarely found in crystals ; it is more frequently disseminated in grains, like sand. Although excessively hard, it is less so than the Oriental. Its colour is black grey, reddish grey, or bluish grey. It is seldom transparent, yet some of its very fine particles shine brightly. The Western emery, which must not be confounded with the granite, magnetic iron, and the compact red hematite, is found in Italy, Germany, and Spain, at Smyrna, in the island of Xasso, at Jersey and Guernsey. That kind which is found in Saxony lies between the strata of mica and steatite. It is united with a great quantity of iron, from which cause it is often attracted by the magnetic needle. 212 GEMS. Emery is most useful in all arts connected with glass, stone, and metal work. It can be reduced into exceedingly fine powder, and when used it is first melted in water, oil, diluted sulphuric acid, or in vinegar. It is often used spread and glued over a strong, stiff card-paper. It is impossible to judge at first sight the quality of an emery. Certain kinds would not do to work stones of medium hardness, being too large in grain. It is remarkable that these are useful in cutting harder stones, and this happens be- cause the grains are then crushed by the hardness of the stone, and reduced to the finest powder. XCII. SPUMA-MARINA. HYDRO-SILICATE of magnesia found in nodules, in various countries, and bearing the above name, from the German word meerschaum, which signifies froth of the sea, because the German labourers who gather it in the Baltic provinces believed that it was produced by the waters of the ocean. XCIII. STALACTITE. THIS name is giyen to certain calcareous spars in th< form of cones, pillars, and columns. STALACTITE. '213 They have a fibrous breakage ; are translucent, of a white or yellowish-white colour, and a smooth or tubercular surface. When water loaded with calcareous matter filters in a cavern, the first drops that drip from the roof leave, after evaporation, a small ring of solid substance, which, by the successive addition of fresh drops, increases in size, while gradually forming a kind of jutting cylinder. Each following drop depositing on the sides of the little cylinder additional solid matter, increases it by degrees, and especially on the upper part, where the drops remain longer, and thus it takes the form of a reversed cone. The watery part which falls from the stalactite on the ground is not totally deprived of calcareous sub- stances, and therefore is not entirely absorbed, but leaves a deposit which rises in the form of an upright cone, and is called stalagmite. Thus the two c mes, always increasing in the same line, frequently join together and form columns, which seem placed there for the support of the roof. If the water, impregnated with calcareous substances, glides slowly over the walls of a grotto, it leaves deposits arranged in festoons or disposed in drapery of most varied form, and these are distinguished from other stalactites by the name of ' drapery configurations.' Stalactites, stalagmites, and these festoons, are seen in many caverns and natural grottoes both in the old and new world. The most celebrated are those of Anti- paros, of Collepardo, of Bauman, and of Monsummano. 214 GEMS. The substance composing stalactites is worked like alabaster, and made into vases, cups, and other little articles. XCIV. TOURMALINE. A GEM remarkable amongst all others on account of its electric qualities. Tourmaline is often found amongst antique jewellery, but we do not know what name the ancients gave to this stone, of which no description remains relative to its physical properties. Equally ignorant are we as to the etymology of its name, which, nevertheless, seems to have come to us from India. In 1717 some German travellers found it at Cey'on and brought it to Europe, calling it ascentrekker, because it especially attracted or repelled ashes. In 1758 an Italian, the Duke of Najo Caraffa, pro- cured two in Amsterdam, which he presented to the celebrated Buffon, who was the first to give a scientific description of them. Then they received the name of electric sciorlo, from the German sciorl, derived from Shorlaw, a Saxon village, in whose environs it was abundantly found. But the term sciorlo is now only applied to the black kind, the others being called touimaline. Tourmaline is found crystallized in pebbles of different forms. The crystals are rhomboidal, and TOPAZ. 215 sometimes very large. It is unequally opaque and semi-transparent. It has vitreous light, and is of all colours of the prism in all their gradations. It cuts quartz, but is cut by the topaz. It gives a white powder. Its breakage is concave and imperfect. Its specific gravity is from 2 ! 99 to 3*33. It has double refraction and great power in polarizing light, which power increases when it is heated. Under the action of the blow-pip'e it swells without melting, while its thin extremities vitrify. United with borax, it easily reduces into a clear and vitreous substance. Tourmaline cut into plates is used in the polaroscope to ascertain the optical properties of other substances. The analyses made of this gem are many and com- plicated, and amongst these the following is the most simple ; it is of the red tourmaline : Silex 43 Alumina .. .. ..47 Soda 10 Tourmaline is found of all colours, and many of them have a great resemblance to the more precious stones, such as the ruby, emerald, and similar. XCY. TOPAZ. THE topaz, like other gems, is divided into two kinds, viz., the Oriental and Western. 216 GEMS. The Oriental topaz is a clear, coloured corundum, of a very bright golden-yellow colour, having a specific gravity of 4. It has double refraction, although in a small degree. It is found in crystals, which are generally round, like those of other corundums, but sometimes it shows its primitive form, which is a quadrangular prism. Its hardness equals that of other corundums. It is found at Peru, Ceylon, and in various other parts of India. With respect to value, it never equals the ruby, sapphire, and emerald. Sometimes it contains little grains which shine like those of the aventurine, but these rather diminish than increase its value. There is a beautiful topaz in the mineralogical cabi- net of Paris 0'023 metres long, and O014 metres wide. The Western topaz is divided into four different kinds, viz., Brazilian, Saxon, Mexican, and Siberian. The Brazilian topaz, which is now most valued next to the Oriental, is generally of a fine, clear deep yellow ; it has such a particular appearance that it is easily recognizable. One of its physical qualities, by which its nature may even better be determined is, that when somewhat heated it acquires electricity, which it preserves some- times for thirty hours. It cuts rock crystal deeply, and its specific weight is 3-52. The most extraordinary of its peculiarities is that of changing colour from yellow to a pink shade when warmed to a certain temperature. This discovery TOPAZ. 217 was made by Damelle in 1750. The rough topaz of Brazil is worth from two to one hundred lire the kilo- gramme, according to colour and purity. The Saxony topaz is generally of a pale yellow ; some have considerable brightness, but these are rare. It changes colour when warmed, then becomes white, but when again cool it resumes its first tint. It is found at Schnaknistein, in the valley of Daneberg. It has no value unless it be very large and very beautiful. The Mexican topaz, which in the two last centuries was called Indian topaz, is almost the same as that of Saxony, only it is more varied in its tints. There is a fine, very clear Siberian topaz, in colour similar to the yellow of the jonquil. Those which are of the aquamarine colour, and are very common, ought not, according to the general opinion, to be reckoned amongst topazes. These various kinds, when analysed, gave Brazilian. Saxony. Siberia. Alumina .. 58 -38 57*45 59 Silex .. .. 34-01 34-24 35 Fluoric acid .. 7-79 7-54 5 We have already observed that the stone called topaz by the ancients is not the topaz of modern times. But if we clearly explained, that to them the chry- solitus was what is now the modern topaz, we did not declare that our chrysolite and the peridot were their topaz. Pliny says, " In our days the green kind of topaz 218 GEMS. (in suo virenti genere) is greatly prized . . . since it is always compared to the juice of the leek . . . and it is one of the noble stones which bears the file." * It is said that its name is derived from topazein, which word, according to him, signifies, in the Troglo- dyte tongue, to seek ; " because " (he continues) " Juba writes that Topazos is an island of the Eed Sea, which, being surrounded by fogs, often requires to be sought out by navigators, whence its name."f We receive it then as a fact that the descriptions handed down to us from the ancients of the stone called topaz by them refer to the modern chrysolite; and all they say of the chrysolite, or golden stone, concerns the modern topaz. I have never seen an intaglio on this stone which could with certainty be called antique. In fact, the topaz, on which is engraved an Indian Bacchus, which came from the Vatican and is preserved in Paris, seems, from the description given of it by Barbot, to have been cut in the seventeenth century. They have also on other topazes the likeness of Philip II. and of Don Carlos, the work of Giacomo da Trezzo, who lived in the sixteenth century. Caire had an Oriental topaz pierced which weighed twenty-nine carats, and on which was cut in Arab letters the little verse, " God alone will finish it." This was probably one of the amulets called by the Arabs gri-gri. * See ' Chrysolite,' page 7. t * Nat. Hist.' xxxvn. viii. 32. TRIPOLI. 210 XCYI. TRIPOLI. THIS mineral substance is not a gem, although necessary to the working of gems ; and therefore all treatises which have mentioned it, have spoken very briefly of it. By the ancients it was called stone of Samos. The name which we give to it now comes from the city of Tripoli, whence it was procured before being found in Europe. It is used principally in giving the last polish to precious stones, and it is useful besides to engravers, opticians, workers in precious metals, gun-makers, and varnishers. It appears that tripoli is a schist or a clay. It is found more or less calcined, and mixed with other schists and clay. On this account it has different degrees of hardness. Analysed by Hasse, it gave Silex 90 Alumina .. .. .. 7 Iron 3 Barbary tripoli comes in commerce in small pieces. That from Polinier, a country near Pompean, and four leagues from Eennes, in France, is harder, and there- fore more in request by the polishers of precious stones. The white kind is preferred, because it is seldom granular. 220 GEMS. In France it is found in a cavern near Menat, in Alvernia. Bomare says that there the banks of this substance are arranged from east to west, and covered with 3,898 metres of earth. He adds that tripoli found there is rather soft, but hardens by contact with the air. XCYII. TURQUOISE. THK Venetians, who were the first to bring this gem into Europe from Turkey, called it turchesa, and after- wards turquina. Turquoise is of three kinds, viz., aluminous Oriental turquoise, fossil or osseous Oriental turquoise, and Western turquoise. The aluminous Oriental turquoise is found in the alluvial lands of India and Persia in globules disposed in lines, or in small fragments. It is of a beautiful sky blue colour, sometime's slightly spotted with green. It is less hard than quartz, but scratches glass, and yields to a good steel file. Notwithstanding its opacity, it takes a beautiful polish. It is insoluble in azotic acid ; and thus it is easily distinguishable from the other kinds. Its specific weight is 3-127. On analysis it gives Alumina .. .. .. 73 Oxide of copper .. .. 4' 5 Oxide of iron . . . . 4 Water 18 TURQUOISE. 221 Fine turquoises of this kind are of a most charming light blue colour, clear and even, at least on one side. It is very rare in large pieces, and therefore of high price. The Oriental fossil turquoise is an osseous animal substance, coloured by oxides of iron and copper, petri- fied by calcareous nitration*. This turquoise is of a blue colour slightly tending to green, and having a smooth surface. It scratches crystal weakly, and resists acids almost like the aluminous species. On analysis it yields Phosphate of lime . . . . 80 Carbonate of lime .. .. 8 Phosphate of iron .. .. 2 Phosphate of magnesia . . 2 Phosphate of manganese .. Traces. The Western turquoises are also osseous substances, generally the teeth of animals, but in a natural state, and not petrified. They are coloured by oxide of copper, and are more likely than the others to discolour under the influence of the air. They lose their colour in distilled water, and dissolve under the action of acids, especially of aquafortis. It is commonly believed that in certain cases every turquoise loses its fine colour. In the middle ages it was asserted that the turquoise grew pale on the finger of a sickly person, but that it regained its colour on the hand of a perfectly healthy person. Others asserted that its colour varied with the hours of 222 GEMS. the day, and insisted that an attentive observer might use it as a sundial. In Germany even now it is be- lieved that, when offered as a love gift, it remains unchanged while love lasts, but loses its colour when affection declines. But if the colour of the Western and that of the fossil Oriental turquoise change, it is not so with the aluminous turquoise, which always remains the same. Fossil turquoises change colour only on the surface, so that they can regain it by means of the wheel. Not so with the Western turquoises, which, changing altogether, can only for some days be made to regain their lost colour by dipping them in a solution of oxide of copper. They are then called bathed turquoise, and are of very little value. Some people think that the turquoise is the stone which the ancients called callais, and is thus described by Pliny : " The callais grows in the islands of Mount Caucasus, .but is spongy and . full of spots : that from Caramania is clearer and better, In both places it is found in inaccessible and cold banks protruding in the form of an eye, which does not appear to have been pro- duced in the stone, but fastened on it. It can be cut and worked, but is fragile. When set in gold, no jewel looks so well. The handsomest , lose their colour in oil, grease, or wine ; the worst preserve theirs best. No stone can be better imitated in glass than this."* Theophrastus is more explicit on this subject, when * Nat. Hist.' xxxvn. viii. 33. VARIOLITE. 223 lie plainly says that callais is a fossil ivory spotted with light and dark blue. All turquoises work smooth. In the East they cut and inlay them with gold. Many engravings in turquoise are thought to be Greek and Roman works. In the Orleans collection there was a turquoise having an engraving of Diana, and another a portrait of Faustina. In the Genevosio collection of Turin Caire saw an amulet having on one side the head of Diana, with a veil on the head, and on the other a cittern, a star and a bee. The Florence gallery had a turquoise which was as large as a small billiard ball, and on which was engraved a likeness of Tiberius. Nevertheless, I think, with King, that there is much reason to doubt the antiquity of these works. For my part, I have never seen engravings on turquoise that were anterior to the twelfth century A.D. But there have been precious ornaments, both Tyrrhenian, Etruscan, Grecian, and Roman, in which I have seen this stone used. XCYIII. VARIOLITE. THIS stone is a dark-green felspar, with grey marks or black spots encircled with white. It is opaque, very dense, very heavy, and emits sparks under steel. It is broken and worked on the 224 GEMS. wheel with difficulty. It takes a very good polish, especially on the spotted parts, as being hardest. This felspar came originally from India. Now it is brought from the Alps, where it is found in pieces of immense size. The appearance of this stone, which has a certain resemblance to the human skin marked by small-pox, created the belief, in times of ignorance, that it had the power of curing that infirmity, for which reason it received the name of variolite. However, it is not always green there are some white, red, and blue. The marks also vary in colour. There are some which, besides the black spot encircled with white, have a second circle of a lighter colour like the onyx. I have never seen antique engravings on variolite, although, on account of the substance of which they are composed, it would be very easy to engrave on "it, especially animals of the feline race. XCIX. VERMILION. THIS stone is divided, like other gems, into Oriental and Western. The Oriental vermilion is of a crimson red, slightly tinged with orange. It is a clear corundum, having a specific weight of 4*2. It is almost as hard as the ruby or the sapphire. I do not know how it was SAPPHIBE. 225 formerly, but at present it is scarce beyond everything. Some have even expressed a doubt as to whether it really exists. Western vermilion is a garnet of a crimson-red colour, inclining somewhat to yellow, and not to black and violet, like other garnets, from which it is dis- tinguished by these qualities. It is very common ; but principally in Germany, as elsewhere, it is only found in small pieces. It has been a question among mineralogists if vermilion is distinct from the garnet, or to be considered simply a variety of it ; nevertheless, goldsmiths, lapidaries, and jewellers easily recognize it, and know that Oriental vermilion is a corundum of great value, and the Western stone differs from garnet, as it is said, in colour, and also in being clearer. c. SAPPHIRE. IN vain have I sought amongst writers for the ety- mology of this word, which was given originally, not to a single gem, but to all stones of a beautiful blue colour. I found that this gem, like the emerald, has almost an identical sound in various languages. Thus in Greek it is called Zapphiros ; in Latin, Sapphirus ; in Hebrew, Sapphir ; in Chaldaic, Sapirinon ; in Syriac, Saphilo ; and in Samaritan, Salia. Q 226 GEMS. The sapphire is also divided into two kinds, viz., Eastern and Western. The Oriental sapphire is a clear corundum, which has all the gradations of blue. It is found only in India, and especially in Ceylon. In hardness it is equal, if not inferior, to that of the red corundum. Its crystals, like those of other corundums, have the primitive form of a dodecahedron with triangular faces, but most frequently they are rounded. Its specific gravity is 4-01. It possesses double refraction in such a degree as to surpass every other stone, not excepting the diamond. It takes its place amongst the translucent and trans- parent gems, and often its imperfect crystallization gives it a milky opacity. Like the ruby, it is composed of alumina almost pure ; its colorization being due to oxide of iron. It is remarkable how the same metallic oxide produces two such different colours in the same stone ; and, whilst remembering that the ruby darkens at the fire, and the sapphire tends to becoming colourless, we must attri- bute this diversity to the greater or less oxidation ex- perienced by the metal at different degrees of heat. The Oriental sapphire, to be considered beautiful, must have a clear blue colour, not too light, and of perfect limpidity. It thus appears soft as velvet, and is so charming that it justifies the simile used by Dante to indicate the clearness and vivacity of the air : SAPPHIRE. 227 " Dolce color d' oriental zaffiro, Che s' accogliena nel sererio aspetto Dell' aer pur, infino al primo giro, Agli occhi miei rincomiucio diletto." Purg. 1* The blue corundum is, however, often defective, having milky spots, white lines, flaws, or nodules, all which must diminish its value. Some of these become more beautiful if exposed to a strong reflected heat in a crucible full of cinders and clay. The celebrated English chemist Brewster, having perceived the great refracting power of the blue corundum, recommended and used it beneficially for microscopic lenses. The price of sapphire is variable. Feuchtwanger gives the following table : Lire. 1 carat .. .. 10 2 .. .. 20 3 .. .. 30 4 .. .. 45 5 .. .. 60 6 .. 80 8 .. 100 10 .. .. 200 * " Sweet colour of the oriental sapphire, That was upgathered in the cloudless aspect Of the pure air, as far as the first circle, Unto mine eyes did recommence delight." Longfellow's trans. 228 GEMS. The Western sapphire is a blue quartz, but it is found of very varied tints, as some stones of this kind are of a greenish blue ; many of a dark blue somewhat inclined to amethyst; others almost all white, but slightly bluish. They receive different names. Thus, French and leaden sapphires are called water sapphires ; but all the stones called Western sapphires are not really such. And I remember that Count Lavinio Spada stated that he had never seen a clear blue quartz, because all the stones that had b*een shown him under that denomination, if really clear, ought rather to have been known as dicroites. The Western sapphire is more frequently dark, and it always has a resinous light. In general its specific weight is 2-580, and its hardness equals that of other quartz. It loses colour under the action of fire. Bluish quartz is found in Silesia, Bohemia, Alsatia, and France, but it also comes from the East, and especially from Ceylon. For ages it has been known that France produces Western sapphires, and even in 1753 a countryman of the village of Expailly obtained a precarious livelihood by seeking these gems in the neighbouring brook called Eiouppezzouliou. There has been much discussion as to what the ancients understood by the name of sapphire. Aristotle and Theophrastus described the zapphiros as a blue gem, covered with spots and veins of gold. Pliny, by the word sapphirus, similarly describes a gem " which shines with gold spots. Sapphires are blue, SAPPHIRE. 229 and very seldom purple. The best are found in Media, but nowhere are they found transparent. Besides this, they are difficult to be worked and useless for the engraver, as they contain certain crystalline spots." Isidore, however, remarks that the " sapphirus ccerulens est cum purpura Jicibens pulveres aureos sparsos" May not this be the lapis-lazuli ? Some modern authors believe the modern sapphire to be the ancient cyanos, of which Pliny writes : " Turquoise stone of a blue colour. . . . The best are found in Scythia; the next best in Cyprus, and after them, in Egypt. They are generally imitated by means of a certain tincture, and the discovery of this is attributed to a king of Egypt. This stone is also divided into masculine and feminine. It sometimes contains dust of gold, not like that of the sapphire." It is generally believed that this substance is the sulphate of copper, which, in its native state, is almost transparent, and of considerable hardness ; this opinion agrees with the description given by Theophrastus* of the cyanos, in which it is clearly seen that the Egyptian imitation of the cyanos is the paste or blue vitrifica- tion which is found in almost all ancient Egyptian ornaments, and still made by modern Egyptian work- men, and called zaffre. But, on the other hand, let us remember what Solino has written : " Amongst the Ethiopian things of which we have spoken, the hyacinthus is of a bright bluish colour : * Chap. 55. 230 GEMS. this stone is highly prized when found without spots, being very subject to defects, so that it is often diminished in value by having a violet tint, clouded with a black shadow, or deadened by a wax tint which whitens it too much." " The best colour for this stone is clear, neither too much dulled by a dark tint, nor too light by excessive transparence, but inclining to a medium colour between blue and purple. This is the gem which is sensitive to the air and sympathises with the heavens, and which does not shine equally whether the firmament is dark or light. Besides this, when put in the mouth, it is colder to the taste than other gems. As to being engraved, it is not very suitable, because not easily cut (attritum respuat) : nevertheless, it is not alto- gether invincible, as it may be cut and engraved in different forms (scribitur et figuratur) by the diamond." From all these descriptions, it appears certain to me that the ancients applied the term sapphirus to some blue stone, like that which we now call zappherine. Besides, they denoted specially under the name of sapphirus that particular stone called by us lapis-lazuli. And that, finally, they gave the name of hyacinthus, without any doubt, to that precious substance now called by us corundum, because in its various forms it is like the different colours of the flower into which Hyacinth, the young friend of Apollo, was changed. And therefore they called the ruby corun- dum hyacinthus purpureus, and the blue corundum hya- cinthus sapphireus. SAPPHIRE. 231 The ancients attributed magical power to the sapphire, and said that it kept away sickness and evil thoughts, whence the ancient distich : " Corporis ardorem refngerat interiorem Sapphirus et Ciprise languida vota facit." It was said to be so inimical to poisons, that when placed in a glass vessel with an asp or any other venomous animal, immediately the animal perished. King says he read in ' San Girolamo ' that the sapphire procures the favour of princes, pacifies enemies, delivers from enchantments, and gains long- desired liberty for the slave. Galen and Dioscorides speak of the medical properties of the sapphire, and consider it an active remedy against fevers. The sapphire was sacred to Apollo, and worn on the back when consulting his oracles. Boezio asserts that this gem preserved chastity, for which reason it was much used by the priests. At present the sapphire is the gem set in the state ring which the cardinals receive in taking the purple. Many beautiful Oriental sapphires furnish the caskets of the sovereigns of every country, for the blue corun- dum is less rare than the ruby. In Europe, one of the most celebrated is now in the Paris Museum ; it was found in Bengal by a poor wood- cutter ; it belonged to the bankers Euspoli, of Borne, from whom it passed to Germany, where a Frenchman, 232 GEMS. named Ferret, "bought it for 170,000 lire; it weighs about 132 carats. There are many very large sapphires in the Eussian treasury. In the French treasury there are 160 that are valued at 600,000 lire. At Dresden, in the green vaults, there were many of remarkable beauty. In the Viennese Kronenschatze is one which is wonderfully large and fine. According to Emanuel, an English gentleman had one, perhaps the finest ever seen, but he sold it, and substituted a false one in the precious ornament which had contained it. This was so like the real one, that the appraiser of the jewels left by him at his death estimated it at 2,500,000 lire, and made the heirs pay legacy duty on it. It is said that the King of Aracan had one as large as a thumb. Most beautiful is that sapphire which belongs to the Borghese of Eome, for which, not many years since, was offered 20,000 gold zechins, or about 235,000 lire. Some authors assert that the sapphire cuts better than the ruby, because it is more easily broken. We find corundums engraved by the ancients, and at the present day they are still engraved. I have how- ever never had the opportunity of seeing blue quartz, that is, Western sapphires, having antique engravings. In the Genevosio collection of Turin there was a white sapphire which had the head of Tiberias en- graved on it. In the Strozzi collection was one with the profile of Hercules. In that of Paris they have a SAPPHIRE. 233 fine sapphire on which is engraved the emperor Per- tinax. It is said there is in the Petersburg Museum a sapphire whose colour varies from whitish to clear blue, and on it is engraved a draped head ; so that the face is white and the folds blue, which produces a beautiful effect. I have a sapphire on which is the head of Vespasian in relievo ; it was found in the Appian Way. It was copied on a blue quartz by the gifted Odelli, a skilful Roman engraver, whose work, in my judgment, succeeded excellently ; but the artist assured me that the quartz cuts very badly on account of the want of closeness in the material. The same artist engraved for me two large blue corundums, and on them he succeeded in giving his work a beautiful finish, because, being harder, they offered more resist- ance to the tool. 234 GEMS. EPILOGUE. AFTER having carefully considered the different gems, and with as much minuteness as I have found possible, it seems to me that it will be useful to collect under the classes, genera and species to which they belong all the substances mentioned in our catalogue, the greater part of which are called precious stones. Let us remember, then, that all the mineral con- stituents of our globe are divided into three great classes, viz. : 1. Minerals combustible. 2. Minerals metallic, or metals. 3. Minerals lithoid, or stones. Amongst gems, the diamond belongs to the first class, that is, the combustibles, and must be con- sidered a variety of carbon properly so called, under the genus of carbonates. With this are compre- hended the carbon, or opaque black diamond, and the boort, or knotted diamond. Of the second class, that is, of metals, it does not fall within my province to speak, because, although gold, silver, platina, and other similar metals, are commonly used ornamentally, and aie called precious metals, we have excluded them from our treatise, because they must not in any degree be identified with gems, and neither could we .speak of them with- EPILOGUE. 235 out a lengthened dissertation on the goldsmith's art, which would have caused us to deviate from the principal subject. Besides, this subject has already been treated by me in a short work entitled DelT Oreficeria antica, and perhaps will be again considered in a more voluminous work. The genera of the third class, to which belong almost all the substances called gems, are, as stated in the introduction, twenty-four; but we need not name them all, those being sufficient which include every substance partaking of the nature and name of precious stones. All gems, then, are arranged under the following genera and orders of the third mineralogical class : The 1st. Non-metallic oxides. 6th. Aluminates. 7th. Aluminous silicates. 8th. Non-aluminous silicates. 9th. Silicates mixed with other components. To the first genus, of non-metallic oxides, belong the species 1st. Of corundum, some of whose varieties are : 1 . The oriental ruby. 5. The oriental amethyst. 2. The oriental sapphire. I 6. The oriental emerald. 3. The oriental aqua- 7. The oriental topaz. marine. 8. The adamantine spar. 4. The oriental alaban- : 9. Emery. dine. 10. The oriental jacinth. 236 GEMS. 2nd. Of the silicates or varieties are : 1 . The agate. 2. The chalcedonyx. 3. The carnelian. 4. The calcedony. 5. The cacholong. 6. The jaspar. 7. The rock crystal. 8. The chrysoprase. 9. The aventurine. 10. The girasol. 11. The iris. 12. The hydrophane. 13. The amethyst. quartz, amongst whose 14. The quartz aqua- marine. 15. The almandine. 16. The xyloidina. 17. The niccolo. 18. The onyx. 19. The cat's eye. 20. The opal. 21. The plasma. 22. The sard. 23. The sard-agate. 24. The sardonyx. To the sixth genus, that is, of the aluminates, belong the species 1st. Of the aluminate of magnesia, amongst whose varieties the principal are : 1. The spinel. | 2. The balais. 2nd. Of aluminate of glucine, amongst whose varieties are : 1. The chrysoberyl. | 2. The cymophane. 3rd. Of the aluminate of copper, amongst whose varieties is reckoned : The turquoise. To the seventh genus of aluminous silicates belong the species EPILOGUE. 237 1st. Of the composite aluminous silicates, amongst whose varieties are : 1. The calcareous garnet. 2. The magnesian garnet. 3. The ferruginous garnet. 4. The manganese garnet. 5. The chrome garnet. 6. The ovarite. 7. The vermilion. 2nd. Of the aluminous silicate of magnesia : some of its varieties are : 1. The dicroite. | 2. The hypersthenum. 3rd. Of the aluminous silicate of glucine : some of its varieties are : 1. The beryl. 2. The emerald. 3. The aquamarine of Ceylon. 4. The prasina. 4th. Of the aluminous silicate of soda: one of its varieties is : Natrolite. 5th. Of the aluminous silicate of lime or of magnesia : amongst its varieties are : 1. The idocrasium. 2. The pyroxenum. 3. The schists. 4. The touchstone. 5. The epidote. 6th. Of the aluminous silicate of lithia, of magnesia or lime : amongst its varieties are : 1. Mica. | 2. Lepidolite. 238 GEMS. 7th. Of felspars : amongst its varieties are : 1. The adularia. 6. The cyanite. 2. The amazzonite. 7. The clorophane. 3. The argentina. 4. The argirite. 8. The labrador. 9. The variolite. 5. The axinite. 10. The porphyry. To the eighth genus of non -aluminous silicates belong the species 1st. Of the silicate of zirconia : amongst its varieties are: 1. The jacinth. I 3. The essonite. 2. The jargoon. 2nd. Of the silicate of magnesia : amongst its varie- ties are : 1. The chrysolite. 2. The olivina. 3. The peridot. 4. The spuma marina, or sea froth. To the ninth genus of united silicates and other composites belong the species 1st. Of the fluoriferous silicates : amongst its varie- ties is found : The topaz. 2nd. Of the sulphuric silicate : amongst its varieties are found : 1. The lapis-lazuli. | 2. The lazulite. EPILOGUE. 239 3rd. Of the silicate of lime and potash : amongst its varieties is found : The hauyna. ith. Of the silicate of borax, magnesia, alumina, &c. : amongst their varieties are : 1. The tourmaline. 2. The rubellite. To the eleventh genus of different carbonates belong the species 1st. Of carbonate of lime: amongst its varieties are : 1. Marble. 2. Alabaster. 3. Stalactite. 4. Alabastrite. 5. Lumachella. 6. Oolite. 7. Pisolite. 2nd. Of carbonate of copper. The principal amongst its varieties is : Malachite. To the fourteenth genus of phosphates belongs Carboniferous phosphate of lime, and amongst its varieties is found : The phosphoric turquoise. To the eighteenth genus of sulphates belongs The sulphate of iron : amongst its varieties are : 1. The marquisite. 2. The hematite. 240 GEMS. Besides the mineralogical classes under which we have arranged the greater part of these gems, there remain some which belong more properly to the vege- table or animal kingdom. Of these I do not give a scientific classification. In the first place, because they are few ; and in the second place, because doing so would lead me into a special treatise foreign to the present subject, and which be- longs more to the province of botanists and zoologists. On this matter it is sufficient for me to say that the precious substances named in this book which, belong- ing to the vegetable kingdom, are used ornamentally, are: 1. Amber. | 2. Gagat. And to the animal kingdom : 1. Ivory. 2. Shells. 3. Coral. 4. Mother-of-pearl. 5. Pearl. I have besides mentioned in my list mosaics, pastes, and enamels of various colours. These, being pro- ductions of art and not of nature, are not included in any class or genus, although mentioned in this treatise because they serve the same purpose as gems. With these observations I conclude my work, suffi- ciently rewarded if, by this effort, I shall in some degree have been an assistance both to those who study precious stones as naturalists, and to those who make it a subject of art and of commerce. EPILOGUE. 241 I do not pretend in this work to teach anything new, or to have made wonderful discoveries, but only to have given a book on gems, in which vis/ collected the best observations hitherto made in works on similar subjects ; my object having always been, both in my work as a goldsmith and by my pen, to promote, in Italy, the further increase and greater glory of the art which I profess. Vale. 16th October, 1869. LONDON : PUINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS. r 'J UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY Return to desk from which borrowed. This book is DUE on the last date stamped below. FEB 2 3 ZU06 11973 SEC 2 8 1974 CWC LD 21-100m-ll,'49(B71468l6)476 w