Part 3

As the colors green and red are the national colors of Russia, and the date of discovery of this stone in Russia occurred on the Emperor’s birthday, the name alexandrite was given to this species of chrysoberyl.

The alexandrite is found in large pieces, but is nearly always flawed and cracked. This is a much-sought-after gem stone, and specimens of from one to five carats command good prices. Up to the present time, however, good alexandrites have been rare, and the demand has always exceeded the supply.

Cat’s-eyes and cymophanes are found in Brazil in alluvial deposits of rivers, and consequently in rolled and rubbed masses.

Chrysoberyls are also found in Russia, Germany, America, Borneo, Pegu, and Moravia.

Chrysolites and topazes are sometimes passed off for chrysoberyls. The chrysolite is, however, lighter and softer, while the topaz becomes electric from heating, and is softer.

Quartz cat’s-eyes, which are mistaken for chrysoberyl or Oriental cat’s-eyes, have a specific gravity of about 2.65, hardness of 6 to 6.5, and are soluble in fluoric acid, besides melting with soda into a clear glass.

They lack the bright, hard polish of the chrysoberyl cat’s-eye, and there should be no difficulty in discovering the difference between the gem and the inferior stone.

ZIRCON.

The zircon, hyacinth, jacinth, or jargoon belong to the tetragonal system of crystallization. The cleavage is imperfect, fracture conchoidal, and specific gravity 4.4 to 4.7, the stone being much heavier than any other gems. Its hardness is 7.5 and lustre vitreous to adamantine, and refraction double to a high degree.

The zircon is phosphorescent when heated; before the blow-pipe it is infusible, but loses its color; and with borax it melts into a transparent glass. Sulphuric acid affects this gem after long maceration.

The composition of the zircon is: zirconia, 66.3; silica, 33.7; with a trace of peroxide of iron.

Under the microscope, the texture of these gems presents a watery appearance, called by the French _ratiné_, and which looks like a liqueur poured into water. This is a strong distinguishing point in the zircon.

The zircon, hyacinth, jargoon, and jacinth are the same gems but of different colors.

The brown, violet, and green colors are known as zircons, the red as hyacinth, the yellow as jacinth, and the grayish-white and white as jargoons.

The jargoon has often been palmed off as a diamond because of its transparent color and adamantine lustre.

The zircon is found in Ceylon, Germany, France, Bohemia, America, and in fact in nearly all parts of the earth, as many as 120 localities having been noted where specimens of the mineral have been discovered.

The zircon can be distinguished from the garnet by its peculiar diamond-like brilliancy and its specific gravity.

TURQUOIS.

The turquois is never found in crystals, but in reniform or stalactitic masses. The color varies from pea- and apple-green to greenish-blue, sky-blue and dark-blue.

The hardness of the turquois is 6., specific gravity 2.6 to 2.8, lustre waxy, and condition opaque to slightly translucent.

Before the reducing flame of the blow-pipe, the turquois does not melt, but becomes brown and colors the flame green. With borax and salts of phosphorus the turquois melts to a clear glass, while it is also soluble in hydrochloric acid. Oriental or mineral turquois is composed of:

Alumina 47.45 Phosphoric acid 27.34 Water 18.18 Oxide of copper 2.02 Iron 1.10 Oxide of manganese 0.50 Phosphate of lime 3.41 ────── 100.00

The best color is a clear deep sky-blue, and in the true turquois this color improves by artificial light; imitation turquoises, however, lose their fine color under the same conditions.

The finest gem turquoises come from the northeastern part of Persia, between Nishapoor and Meshed. Here they are mined and partly cut, and then the Persian merchants carry them to Russia, where they are sold at the great annual fair of Nijni-Novgorod and in Moscow. Mineral turquoises are also found in New Mexico, Arizona, and Nevada, but not of sufficient size or sufficiently good color to make gem stones, although they are prized for collections. Specimens are also found in Burmah, Khorassan, Thibet, China, Silesia, Saxony, and on the Isthmus of Suez. The stones from these places have, as a rule, but little value, as the color fades or turns green from exposure to the light. Of late however, some very good turquoises have come from Egypt. The color of a faded Persian turquois can sometimes be restored by simply repolishing the stone.

Occidental or bone turquoises called new rock or odontolites, to distinguish them from the Persian or old rock stones, are of organic origin.

They are cut from the teeth of mammoths, mastodons, dinotheriums, etc., and are found near the town of Simor, in Lower Languedoc, France.

These teeth, the enamel of which is nearly as hard as the mineral turquois, are colored by contact with phosphate of iron and copper, which gives them a dark-blue, light-blue, and bluish-green color. They are easily attacked by a file, and totally destroyed by aqua-fortis.

When heated, the fossil turquois or odontolite gives an offensive odor, owing to the decomposition of animal matter.

The odontolite is lighter than the mineral turquois, changes color by artificial light, loses color in distilled water and alcohol, and is translucent on the edges.

This fossil turquois does not fade like the mineral turquois, but by artificial light appears of a dirty grayish-blue.

Turquoises are sometimes artificially stained, but this can be detected by applying a drop of ammonia to the back of the stone, and if the color is artificial the ammonia will eat it off, leaving a green spot. Ammonia does not affect the color of the Persian turquois. The so-called “reconstructed” turquoises are very close imitations of the real, but are easily distinguished, as they change rapidly to a deeper blue when immersed in water, and while wet the surface of the stone shows cracks in every direction. These stones become softer through soaking in water or alcohol. The original color, however, returns when the stone is dry, but the cracks remain in faint outline.

TOURMALINE.

The tourmaline or precious schorl is known under many different names, and no other mineral has such a suite of colors.

The colorless variety is known as achroite; the red, as rubellite or siberite; the blue, indicolite or Brazilian sapphire; the green, Brazilian emerald; and the yellowish-green, Ceylon chrysolite or Ceylon peridot. Besides the above colors and their shadings, the tourmaline occurs in black and brown.

The crystallization is obtuse rhomboid, and generally forms six-, nine-, and twelve-sided prisms.

Some of the crystals are very large, specimens over eight inches long having been mined.

The tourmaline crystals are remarkable for their varied and beautiful groupings of colors. Some are internally blue or brown, surrounded by a bright carmine red or dull yellow; others are red internally and are enveloped by a green exterior; crystals are sometimes pink at the summit and light green at the base, or crimson tipped with black, or white at one end shading into green and finally into red at the other end. The hardness of the tourmaline is 7 to 7.5, specific gravity 3 to 3.1, and lustre vitreous.

The tourmaline becomes decidedly electric by heating or rubbing, and will readily attract small pieces of paper and other small objects. The rubellite or red tourmaline is composed of:

Silica 42.13 Alumina 36.43 Boracic acid 5.74 Oxide of manganese 6.32 Lime 1.20 Potash 2.41 Lithia 2.04

The green tourmaline is composed of

Silica 40. Alumina 39.16 Lithia and potash 3.59 Protoxide of iron 5.96 Protoxide of manganese 2.14 Boracic acid 4.59 Volatile matter 1.58

The tourmaline possesses double refraction to a high degree, and its power of polarizing light is so great that, cut into slices, it is used in the polariscope for analyzing other minerals.

If two slices of tourmaline, cut parallel to their axis, be laid one on the other in one direction, both are transparent; if laid in another direction they become opaque, and if a doubly refracting crystal be placed between the two plates of tourmaline, the part covered by the crystal is transparent while the other is opaque.

Tourmaline melts with borax into a transparent glass; the rubellite turns white, and the indicolite and green tourmalines turn black, under the blow-pipe.

Tourmalines can be distinguished from other gems by their specific gravity, but principally by their property of assuming polaric electricity after being heated, one end becoming positive and the other negative.

The history of the discovery of the tourmaline and its electric property is a curious one.

On a warm summer day, early in the eighteenth century, some children were playing in a courtyard in Amsterdam. Amongst their playthings were some precious stones which the Dutch navigators had brought from Ceylon. Some of the stones seemed to be possessed of the strange power of attracting and repelling small bits of straw, ashes, and other light substances. The little ones called their parents to witness this strange phenomenon, and the stolid Dutch lapidaries, themselves puzzled at the sight, called the stones _aschentreckers_ or ash-drawers.

A number of years afterwards, careful experiments disclosed the wonderful electric powers of the aschentreckers or tourmalines. Purple, green, and blue tourmalines are found in Brazil. In Ceylon the stones are found in gravel beds. Rubellites or siberites are found in Siberia.

Tourmalines are also found in Moravia, the island of Elba, Sweden, Burmah, Tyrol, Canada, and the United States.

The first tourmaline deposits known in the United States were discovered at Paris, Maine, in 1820. Another wonderful deposit was found at Mt. Apatite in Maine in 1882, and up to the present time the finest tourmaline crystals have been discovered in the United States.

Really fine specimens of red, blue, or green tourmalines are uncommon and command very good prices.

OPAL.

The precious or noble opal, fire opal, common opal, hydrophane, and cachelong are different varieties of a mineral that is composed of about nine parts silica and one part water.

The colors vary from chalky-white to bluish-white, from yellow to red, and from a slight play of colors to the beautiful mingling of green, blue, and red with the most remarkable kaleidoscopic effects.

The opal is 5.5 to 6 in hardness, specific gravity 2 to 2.1, lustre glassy, and translucent from a slight to a very high degree.

The opal is found in an amorphous state and never crystallizes; in fact from the condition of the pockets in which this mineral is found, the indications are that the substance was once a fluid.

Under the blow-pipe the opal loses its translucency and cracks but does not melt. Sulphuric acid will cause it to turn black, and in a cold solution of caustic potash the opal is almost entirely soluble.

The precious or noble opal is found chiefly in the mines of Czernowitza, between Kaschau and Eperies, in Hungary, and in Gracias á Dios, a province in Honduras.

In olden times, the Greek and Turkish merchants carried opals from Hungary to the Orient, and then they were shipped to Holland and sold in Europe as Oriental opals.

The fire opal is of a yellowish-red color, and is found chiefly in Mexico, although it also occurs in Hungary, the Faroe Islands, Honduras, and Guatemala.

The common opal is found in Ireland, Denmark, Frankfurt, Guatemala, and South Australia, and also in Hungary and Mexico. These opals are translucent without fire or reflection.

The hydrophane is an opal that has lost color and brilliancy by reason of the evaporation of its water. If placed in water or alcohol, this stone becomes transparent, only to lose this quality when the water or alcohol has evaporated.

The hydrophane becomes transparent more quickly in warm than in cold water, but most rapidly in alcohol. If boiled in oil, the hydrophane is said to retain its brilliancy for years.

The cachelong is milky-white, and nearly opaque, and is found in small masses in the river Cach, in Bucharia, and also in Iceland.

Although one of the most magnificent of the gem stones, the opal for many years was under the ban of superstition. Now, this splendid stone once more commands a foremost place in the jewelers’ art, and the opal mines of Hungary and Queensland are being worked to their fullest extent to supply the demand.

PEARL.

Although an organic product, the pearl is always ranked amongst the most precious of gems, and is distinguished by being the only gem that does not require the lapidary’s touch to bring out its beauties.

Ancient writers have accounted for the origin of pearls by saying that they were formed of angels’ tears, or drops of dew from heaven, which, during the midsummer nights, fell into the gaping mouths of the pearl-oysters.

According to modern scientific investigation, the formation of the pearl does not seem to be the result of healthy natural causes, but comes from the efforts of the oyster to rid itself of some foreign substance, like a grain of sand, a bit of shell or vegetation, or some unwelcome visitor in the shape of a small water insect.

When annoyed by an intruding substance, the oyster begins to deposit its nacre, or mother-of-pearl, in regular concentric layers around the intruder, these layers gradually increasing in circumference and forming the pearl. Thus, like an onion, the pearl is merely a succession of layers or skins, starting from a small core, or nucleus, which is always present, though often only of microscopical size.

Pearls have sometimes been found where the outer layer, or skin, as it is technically called, has been discolored or otherwise injured, and when this top skin has been carefully removed the result was a somewhat smaller but perfect pearl.

This, however, is a very delicate operation, and at the pearling grounds is only resorted to by men of experience. The composition of the pearl is carbonate of lime, with a small proportion of organic matter, and the specific gravity 2.5 to 2.7.

The pearl is affected by acids, and is easily calcined on exposure to heat.

In color, the pure white, slightly transparent, is the most highly prized; while in India and China the bright yellow colors are sought after.

Decided colors, however, such as black, pink, and golden-yellow bring a high price, and, in fact, black pearls, if perfect in color and shape, are at present more valuable than any other kind.

The beauty and value of a pearl depend on form, quality of texture or skin, color, transparency or water, and lustre or orient.

In form, the perfectly round shape comes first in value, then a finely formed drop or pear shape, and lastly the oval or egg shape.

Pearls that are flat on one side and rounded on the other are called boutons or button pearls. These are frequently found attached to the shell, and are cut out and the bottom part smoothed and polished.

It is easy, however, to detect this class of pearls by the lack of pearly lustre on the side that was attached to the shell.

When a pearl is rough and odd-shaped it is called a baroque, and some extremely fantastic shapes are found, especially in fresh-water oysters.

The texture or skin of a fine pearl should be perfectly smooth and free from all spots, indentations, wrinkles, or scratches.

Pure white is the desirable color for a gem pearl, but many others that are slightly tinted with blue, pink, or yellow will pass for gems if they are otherwise perfect.

The transparency or “water” of a pearl, while not existing in fact, is still one of the requisites of a fine pearl; there must be an appearance of transparency, which adds to the beauty of the gem.

To describe the lustre or orient of the pearl, the author can only use the term pearly, as there is no other substance that approaches the brilliancy and color of a pearl, excepting, of course, mother-of-pearl—the nacre in the pearl-oyster.

Without orient or lustre, the pearl of finest form and color has but little value.

Lustre is to the pearl what brilliancy is to the diamond; when the orient is absent there is no life, no beauty.

Pearls are principally supplied by two groups of pearl-oysters or mussels: the marine or meleagrina margaritifera, a round-cornered square shell with very thick sides, measuring six to eight inches in length.

The color of this shell is mostly blackish-green, but it is also sometimes yellowish; the edges of the inner part of the shell are black, but the rest of the interior is the beautiful mother-of-pearl.

The oyster itself is small for the size of the shell.

This specimen is found on the coast of Ceylon, Persian Gulf, Japanese, Mexican and California coasts, the western shores of South America, Brazil, West Indian Islands, Panama, Sooloo Archipelago, and the northeast and northwestern coast of Australia.

The fresh-water or unio margaritifera is an even, egg-shaped mussel found in brooks, rivers, and lakes in temperate zones in nearly all parts of the world.

Some fine river pearls have been found in the United States, but most of the American pearls are of a button or elongated shape, or are baroques or fancy-shaped.

In China many people engage in the business of making small pellets of clay or metal images, which in the month of May are introduced into the river mussels (mytilus cygneus).

The mussels are replanted, and in November they are taken up again. Some of the oysters die, but most of them are found to have been actively at work covering the little pellets or metal figures with nacre, and while no strictly first-class pearls are formed in this way, many curious little pearl figures or gods are made and sold to the curious or devout.

Pink or conch pearls are found in the Gulf of California and coasts of Mexico, Bahama Islands, West Indian Islands, and in some rivers in South America.

They seldom occur in regular shapes, and although they are termed pink pearls, they range in color from red to pale yellow, and are often found of a china-white color.

The pink pearl displays a wavy appearance and a peculiar sheen, something like watered silk. As the pink pearl is seldom found perfectly round and of a good color, such a specimen is very valuable.

CHRYSOLITE.

The chrysolite, peridot, and olivine differ in color, but are practically of the same composition.

The chrysolite proper is of a pale greenish-yellow color, the peridot a deep olive-green, and the olivine of a yellowish or light olive-green color; these stones also shade into brown. They crystallize on the rhombic system, are transparent to translucent, 6.5 to 7. in the scale of hardness, and 3.3 to 3.5 in specific gravity.

The cleavage is distinct, fracture conchoidal, refraction double, and lustre vitreous, and in the olivines somewhat greasy.

These stones are easily affected by sulphuric acid, but are infusible before the blow-pipe, excepting some kinds containing much iron.

With borax, they melt to a pale-green transparent glass.

Chrysolites are composed of silica, magnesia, and oxide of iron.

Perfectly crystallized chrysolites are brought from Constantinople, but the exact locality where they are found is unknown.

Less distinct specimens occur at Vesuvius, Mexico, the isle of Bourbon, Auvergne, Egypt, Natolia, Brazil, Germany, Pegu, Ceylon, Switzerland, and North America.

Peridots are distinguished by being the only precious stones that have literally dropped from heaven, as they have been found in meteorites.

The Oriental chrysolite of commerce is true chrysoberyl, and is harder and heavier than chrysolite, and the stone called Ceylon chrysolite is a greenish-yellow tourmaline, which is easily distinguished, as it is also harder while considerably lighter than the chrysolite.

The green garnet is of a pronounced green color, and is harder and heavier than the olivine or chrysolite. Although suitable for mounting in brooches and other ornaments, these stones are not sufficiently hard for the rough usage as ring-stones.

GARNET.

Almandine, almandite, Syrian garnet, essonite, cinnamon-stone, pyrope, Bohemian garnet, vermeille, Cape garnet, Cape ruby, Arizona ruby, American ruby, carbuncle, uwarowite, demantoide, grossularite, and Bobrowska garnet are some of the scientific and commercial names for different species and colors of the garnet group.

The crystallization of the garnet is isometric, refraction single, specific gravity 3.15 to 4.3, hardness 5 to 8, lustre vitreous, fracture uneven, colors red, violet, brown, yellow, green, and white, and the various shadings of these colors.

Most varieties fuse easily to a brown or black glass; the uwarowite fuses with borax to a clear chrome-green glass.

Syrian, almandine, almandite, and carbuncle are different names for the iron-alumina garnet.

In colors, these stones shade from deep-red to violet and brownish-red, and are composed of:

Silica 36.01 Alumina 20.06 Protoxide of iron 43.03

The specific gravity is 4. to 4.2, and hardness 7.5.

This garnet, sometimes called the precious garnet, is found in Ceylon, Pegu, Brazil, Greenland, Hindustan, Bohemia, Tyrol, Œtzthal, Carinthia, Styria, Switzerland, Ariolo, Canaria, Maggia, Hungary, Sweden, Norway, Scotland, Spain, and the United States.

Grossularite, or lime-alumina garnet, is known in commerce as essonite, or cinnamon-stone. The color is yellow, of various shades; specific gravity 3.5 to 3.65, and hardness 6.5.

These stones are sometimes sold for jacinths, but they are softer than the jacinth, and melt easily before the blow-pipe. Essonites come principally from Ceylon, but are also found in other places.

Pyrope or Bohemian garnet is the magnesia-alumina variety, and is of a uniform dark blood-red color. This stone is found in Bohemia, and although quantities of small pieces are found, large specimens are rare, and a piece that will cut into a four- or five-carat stone is seldom met with and commands a high price.

These garnets are found at Stiefelburg by Meronitz, Triblitz, Podsedlitz, and Neupaka.

The pyrope turns black under the blow-pipe, then red again, and melts with difficulty into a black glass. With borax it melts to an emerald-green glass. The specific gravity of this garnet is 3.69 to 3.78, and hardness 7.5.

Vermeille is a name given to the orange-red almandine, Cape garnet to the bright red-yellow variety, Cape ruby to the pyrope, and American ruby to the blood-red kind found in New Mexico, Montana, and Arizona. Carbuncle is a term applied _to all_ garnets cut with a smooth rounding top, sometimes called, after the French, cabochon.

Uwarowite or lime-chrome garnet is one of the rarest and most beautiful of the garnet group.

The color of this stone is emerald-green, hardness 7.5, and specific gravity 3.41 to 3.52. Uwarowites are found near Bissersk in the Urals of Russia, but rarely in specimens of sufficient size to cut into gems.

This garnet is heavier and harder than the true emerald.

Demantoide or Bobrowska garnet is a soft garnet, olive-green to brown and blackish-green in color, sometimes light green. It is found in the Bobrowska River in the Urals. The specific gravity is 3.85, and hardness about 6, its softness making it undesirable for many ornaments. Before the blow-pipe it fuses into a black bead.

These garnets are often sold as olivines; they are heavier than olivines and softer.