Birds and Nature Vol. 11 No. 3 [March 1902]

“The Opal, when pure and uncut in its native rock,” says Ruskin in his lecture on Color, “presents the most lovely colors that can be seen in the world except those of clouds.”

While not all of us may share the great art critic’s preference for uncut stones, there are few probably who will not join him heartily in his admiration of the brilliant gem from whose depths come welling up tints of so varied hue that we appropriately speak of them as colors at play. Our interest in these colors may be heightened by reading what Ruskin has further to say of them: “We have thus in nature, chiefly obtained by crystalline conditions, a series of groups of entirely delicious hues; and it is one of the best signs that the bodily system is in a healthy state when we can see these clearly in their most delicate tints and enjoy them fully and simply with the kind of enjoyment that children have in eating sweet things. I shall place a piece of rock opal on the table in your working room; and if on fine days you will sometimes dip it in water, take it into sunshine and examine it with a lens of moderate power, you may always test your progress in sensibility to color by the degree of pleasure it gives you.”

The Opal is indeed one of the most fascinating of gems; yet often elusive and at times disappointing. Of its freaks and foibles strange stories are told. Gems of brilliant quality are known suddenly to have lost their hues never to regain them, while others previously dull and lusterless have become radiant as the rainbow.

Prof. Egleston, of New York city, relates that a bottle of cut Opals once given him by a prominent jewelry firm because they had lost their color, after remaining in his cabinet for a time regained their brilliancy and retained it. But to have opals regain their color is, unfortunately, far less usual than for them to lose it. The gem often exhibits brilliant colors when wet either with water or oil that disappear when it is dry. Taking advantage of this peculiarity dishonest dealers often keep opals immersed until just before offering them for sale. The experience of having stones so treated as well as others which might with more reason be expected to retain their brilliancy, lose it, has very likely led to the superstition commonly attached to the Opal that it is an unlucky gem. Some authorities, however, trace the origin of the superstition to Sir Walter Scott’s novel, “Anne of Geierstein,” in which the baleful influence of the Opal plays a prominent part, and it is stated that within a year of the publication of the book the price of Opals declined fifty per cent in the European market. Even if the superstition did not originate in either of these ways it was probably from a source quite as trivial and it should prevent no one from enjoying the pleasure to be derived from the beauties of this gem.

Chemically, Opal is oxide of silicon with varying amounts of water, the water varying from 3 to 9 per cent. It is, therefore, closely allied to quartz, but differs physically in being softer and not as heavy. Further, it never crystallizes, and it is soluble in caustic potash, which quartz is not. It is infusible, but cracks and becomes opaque before the blowpipe. In sulphuric acid it turns black, on account probably of the organic matter it contains.

Its hardness is sometimes as low as 5.5 in the scale in which quartz is 7 and its specific gravity is from 1.9 to 2.3, while that of quartz is 2.6. On account of its relative softness a cut Opal often does not retain its polish well and requires frequent smoothing. Opals when first taken from the ground are often softer even than the above and for this reason it is usual and desirable to allow them to harden or “season,” as it is called, for some time after quarrying, before they are polished.

Opal as a mineral is quite common, so that no one need suppose because he has specimens labeled “opal” in his collection that he has as many precious stones. It occurs in many varieties, and, especially if it contains foreign matter, in many colors. Nearly all silica deposited by hot waters is in the form of Opal, so that the geysers of Yellowstone Park build up cones of Opal and fall into Opal basins. This particular form of Opal is known as geyserite, and it is often differently colored by different ingredients.

Wood is often preserved by silica in the form of Opal, the siliceous waters taking away the wood and replacing it by Opal, grain by grain, with such delicacy and accuracy that the structure of the wood is perfectly maintained. The minute shells which diatoms make consist of Opal, and when these dead shells accumulate to form deposits of some extent we call the powdery substance tripoli and use it for polishing silverware and other metals. Then there are hyalite, a variety of Opal looking like transfixed water, so clear and colorless is it; hydrophane, a translucent variety which sticks to the tongue and becomes more nearly transparent when soaked in water; cacholong, a porcelain-like variety, and menilite, a concretionary variety.

Common Opal varies from transparent to opaque, being most often translucent and sometimes exhibiting the peculiar milkiness of color which we call opalescence. It has sometimes a glassy, but often a waxy luster, the latter when pronounced giving rise to the varieties known as wax Opal and resin Opal. When Opal has the banded structure of agate it is known as Opal-agate; when it has the color of jasper as jasper Opal, and when that of chrysoprase as prase Opal. But none of these varieties are used in any quantity as gems. This distinction is reserved almost wholly for the variety known as noble or precious Opal. This is Opal which exhibits a play of colors. No essential chemical or physical distinction between noble Opal and other varieties is known. In a large vein of Opal portions will exhibit the play of colors and the remainder will not, but why the difference has not yet been determined. Neither can the origin of the varied coloring; i. e., the iridescence, be determined. Some regard it as due to interspersed layers containing different percentages of water, which break up the rays of light somewhat as a prism does, while others think that minute cracks and fissures through the stone furnish surfaces from which the rays are reflected in different colors back to the eye. Some Opals which are dull and lusterless when dry exhibit considerable play of color when immersed in water, and this fact seems to favor the first theory of the cause of the iridescence, but the subject is not understood. The character of the play of colors differs in different Opals, and this gives rise to different varieties. The true noble Opal has the color quite uniformly distributed. When the color appears in flashes of red, yellow, etc., the stone is known as fire Opal; if blue as girasol, and if chiefly yellow as golden Opal. When the patches of color are small, angular and uniformly distributed it is called harlequin Opal, and if these are long and somewhat parallel, flame Opal. These colors are not, of course, inherent in the stone, its color varying from colorless to opaque white. The black Opals sometimes seen and highly prized by some are usually artificial, and are made by soaking ordinary Opals in oil and then burning oil on them. The brilliancy of the stone is thus increased, but it is usually fragile and liable to lose color.

Any Opal will lose its play of colors on being heated too highly, hence possessors should avoid subjecting them to more than ordinary heat. It is the variety and brilliancy of their changing colors which give to Opal nearly all its desirability as a precious stone, for, as has often been remarked, the qualities of hardness, transparency and rich body color which give to most other gems their value are lacking in the Opal. But together with the beauty of its changing colors Opal possesses an advantage over all other gems in that it cannot be successfully imitated. It is said that the Romans were able to make artificial Opals closely resembling the real, but, if so, the art has been lost never to be recovered, and we may hope it never will be. Hence, however much danger there may be in buying an Opal that it has not been properly “seasoned,” or may not retain its color, the purchaser may at least be sure he has an Opal and not an imitation. The stones are usually cut in the oval form known as en cabouchon, this cutting being found to bring out their brilliancy better than any facetted form. The brilliancy of the stone may be increased in setting by giving it a backing of mother of pearl or black silk. When a number of Opals are placed together they seem to borrow brilliancy from one another, a fact which is taken advantage of in settings by placing a number together and also by Opal dealers to dispose of inferior stones by grouping them with good ones. For this reason when Opals are purchased they should be examined separately. The value of Opals depends almost wholly on the brilliancy of their coloring and their size. Stones without the play of colors are practically worthless, while stones of ten to twenty carats’ weight, with brilliant coloring, may bring several hundred dollars. The most highly valued Opals have long come from the mines of Czernowitza in northern Hungary. These Opals are often known as Oriental Opals from the fact that in early days they were first purchased by Greek and Turkish merchants, and by them sent to Holland. There are, however, no localities in the Orient where precious Opals are found. The rock in which the Hungarian Opals occur is eruptive, and of the kind known as andesite. It is considerably decomposed, and the Opal occurs in clefts and veins. There is little doubt that it was from these mines that the Romans obtained the Opals known to them, and the output has been quite constant since.

It is said that the Hungarian Opals are less likely to deteriorate than any others. Still the danger of deterioration is not great in any Opal. The other important countries from which precious Opals are obtained are Mexico, Honduras and Australia. The Mexican Opals are mostly of the fire Opal variety. They are mined in a number of the States of the Republic – Queretaro, Hidalgo, Guerrero, Michoacan, Jalisco and San Luis Potosi. The oldest mines are in the State of Hidalgo, near Zimapan, where the Opal occurs in a red trachyte. Most of the Mexican Opals on the market at the present time, however, come from the State of Queretaro, where mining for them is conducted on a more extensive scale. The Opal here occurs in long veins in a porphyritic trachyte, and is mined at various points. The stones are cut and polished by workmen in the city of Queretaro who use ordinary grind-stones and chamois skins for the work and are said to receive an average wage of 23 cents a day.

The Honduras Opals reach foreign markets but rarely and usually uncut. The mines are in the western part of Honduras, in the Department of Gracias. They are little worked, but there is no doubt that extensive deposits exist which might afford a good supply of gems if they were properly exploited. The Australian Opals come from several localities, the most prominent at the present time being White Cliffs, New South Wales. The matrix is a Cretaceous sandstone which has been permeated by hot volcanic waters. Shells, bones and other fossils are found here entirely altered to precious Opal, making objects of great beauty. In 1899 Opals to the value of $650,000 were sold from this single region. There is no doubt that the present popularity of the Opal is due to some extent to the supply of beautiful stones which has come from these mines at prices at from one-third to one-tenth those of the Hungarian stones. Other localities in Australia whence precious Opals are obtained are places on the Barcoo River and Bulla Creek, Queensland, and occasional finds in West Australia.

No localities in the United States yielding precious Opals in any quantity have yet been discovered. Some good stones have been cut from an occurrence in Idaho, and some other minor finds have been made, but they possess little commercial importance at present.

Opal does not seem to have been extensively known or used by the ancients, although we know the Romans prized it highly and ascribed to it the power of warning against disaster. The Roman Senator Nonius owned one set in a ring which was said to be valued at nearly a million dollars. History records that for refusing to sell the stone to Mark Antony he was sent into exile. The next most famous Opal in history is one owned by the Empress Josephine which was called “The Burning of Troy,” on account of the brilliancy of the flames which shot forth from its depths. The present whereabouts of neither of these gems is known. A large Mexican Opal, now in the Field Columbian Museum, is carved in the image of the Mexican sun-god, and has a setting of gold representing the diverging rays of the sun. This gem is very ancient and is believed to have been kept by the Aztecs in a temple, so it is probable that the Aztecs knew and prized Opals.

The Arabians believe that Opals fall from heaven with the lightning’s flash, a beautiful fancy, indeed. Modern usage makes the Opal the birthstone of the month of October, some of the properties assigned to it being that it has the power of making its wearer a general favorite, enhancing the keenness of his sight and shielding him from suicide.

October’s child is born for woe
And life’s vicissitudes must know;
But lay an Opal on her breast
And Hope will lull those woes to rest.

    Oliver Cummings Farrington.

THE CROCUS

“Rest, little sister,” her sisters said —
Violet purple and wild-rose red —
“Rest, dear, yet, till the sun comes out,
Till the hedges bud, and the grass blades sprout.
We are safe in the kindly earth, and warm —
In the upper world there is sleet and storm.
Oh, wait for the robin’s true, clear note,
For the sound of a drifting wing afloat;
For the laughter bright of an April shower
To call and wake you, sweet Crocus flower.”

But brave-heart Crocus said never a word,
Nor paused to listen for note of bird,
Or laugh of raindrop * * * In rough green vest
And golden bonnet, herself she dressed
By the light of a glow worm’s friendly spark,
And softly crept up the stairway dark,
Out through the portal of frozen mold
Into the wide world, bleak and cold.
But somehow a sunbeam found the place
Where the snow made room for her lifted face.

    – Madeline S. Bridges, in Ladies’ Home Journal.

MARCH

The stormy March is come at last,
With wind and cloud and changing skies;
I hear the rushing of the blast,
That through the snowy valley flies.

Ah, passing few are they who speak,
Wild, stormy month, in praise of thee;
Yet, though thy winds are loud and bleak,
Thou art welcome month to me.

For thou, to Northern lands again,
The glad and glorious sun dost bring,
And thou hast joined the gentle train
And wear’st the gentle name of Spring.

And, in thy reign of blast and storm,
Smiles many a long, bright sunny day,
When the changed winds are soft and warm,
And heaven puts on the blue of May.

Then sing aloud the gushing rills
And the full springs, from frosts set free,
That, brightly leaping down the hills,
Are just sent out to meet the sea.

The year’s departing beauty hides
Of wintry storms the sullen threat;
But in thy sternest frown abides
A look of kindly promise yet.

Thou bring’st the hope of those calm skies,
And that soft time of many showers,
When the wide bloom, on earth that lies,
Seems of a brighter world than ours.