Buch lesen: «Birds and Nature Vol. 10 No. 5 [December 1901]», Seite 4

TOPAZ

Remarkable clearness and transparency, capacity of taking a high polish and hardness and weight greater than that of quartz. These are the qualities in which Topaz excels as a gem. Numerous other stones of inferior quality masquerade under its name, however, and this fact may account for the decline in popularity which the stone has suffered in recent years. True Topaz is a silicate of alumina, containing hydroxyl and fluorine. Its hardness is 8 in the scale in which quartz is 7. Hence it will scratch the latter mineral and may thus be distinguished from it. It is also remarkably heavy, considering its composition, it being three and one-half times as heavy as water, while quartz is only two and one-half times as heavy. Owing to this unusual specific gravity, experts accustomed to handling gems can frequently pick out the Topaz from a miscellaneous lot of precious stones without removing their wrappings.

The color typically associated with Topaz in its use as a gem is yellow. Yet the mineral species exhibits many other shades of color, which, when present in crystals of sufficient clearness and purity, answer equally well for gem purposes. These other shades, most of which are represented in the accompanying plate, are grayish, greenish, bluish and reddish. Topaz may also be quite colorless. The yellow color of the Brazilian Topaz can be changed by heating to a pale rose pink and the gem is often treated in this way. The degree of heat employed is not high, and both heating and cooling must be performed gradually. Warming in a sand bath at a low red heat is the method usually employed, or the stone may be wrapped in German tinder and the latter set on fire. Only stones of a brown yellow color yield the pink; the pale yellow stones turn white when so treated. Once the pink color is obtained it is permanent. The natural colors of Topaz are in general perfectly durable, although some of the deep wine yellow Topazes from Russia fade on exposure to daylight.

Topaz is infusible before the blowpipe. It is not affected by hydrochloric acid, but is partially decomposed by sulphuric acid and then yields hydrofluoric acid. If the latter experiment is tried in a closed glass tube the formation of the hydrofluoric acid is made evident by the etching and clouding of the walls of the tube. The powdered stone should be mixed with acid sulphate of potash for this experiment. The powdered mineral, when heated with cobalt nitrate, assumes a fine blue color, due to the alumina which it contains. One of the most convenient means of distinguishing Topaz from other stones used to imitate it is through its property of becoming electric by heat, friction or pressure. This electrical condition is evidenced, as in the case of tourmaline, by the power the stone acquires to pick up and hold bits of tissue paper, straws, etc. Sometimes the friction from merely rubbing the stone between the fingers will be sufficient to produce this electrical condition, while many Brazilian Topazes, if simply pressed between the fingers, especially in the direction of the prismatic axis, become electric. The electrical condition often persists from twenty-four to thirty hours.

The crystals of Topaz belong to the orthorhombic system of crystallization. They are usually elongated in the direction of the prism and have sharp, bright faces. They vary much in size and often are large. One crystal weighing twenty-five pounds was found in Siberia.

A well-marked characteristic of all Topaz crystals is their tendency to cleave across the prism parallel with its base. Such a cleavage plane can be seen cutting across the crystal shown in the upper right-hand corner of the accompanying plate. This cleavage is so marked and the cleavage plane so bright and flat that in cutting Topaz for a gem a cleavage surface is used as the upper face of the gem and the other faces formed around it. Owing to this easy cleavage the owner of a cut Topaz should be careful not to let the stone drop, as it might be cracked or broken.

The name Topaz is derived from the Greek name topazios, which is that of an island in the Red Sea. The gem known to the ancients as topaz, however, was not our Topaz, but the mineral chrysolite. Topaz usually occurs in gneiss or granite, with tourmaline, mica, beryl, etc. In Brazil it occurs in a talcose rock or in mica slate. It is sometimes in sufficient abundance to form an essential rock constituent. When so occurring, however, it has not the transparent gem quality, but is white and opaque. Much of the Brazilian Topaz occurs as rolled pebbles, one of which is shown in the accompanying plate. These occur in the beds of streams, having been left behind owing to their superior hardness after the rock in which they were formed has been washed away. When colorless they are known in the region as “pingos d’Agua” (drops of water). The Portuguese call them “slaves’ diamonds.” A stone in the crown of Portugal, reputed to be a diamond of 1,680 carats weight and called the Braganza, is undoubtedly only a Topaz of exceptional clearness and beauty.

The Brazilian Topazes come mostly from the Province of Minas Geraes, the province which also yields diamonds, beryls and many other precious stones. While those of greenish and bluish shades are found mostly in the form of rolled pebbles the yellow Brazilian Topaz is found in the mother rock. This is a decomposed itacolumite of a white or yellow color. The Russian Topazes, like that shown in the plate, come from the Imperial mines in the Urals. Alabashka, near Mursinka, is one of the most productive localities. The crystals occur in cavities in granite and are accompanied by crystals of smoky quartz, feldspar and mica. Superb gems are cut from these Topazes, a fine series of which is possessed by the Field Columbian Museum. The mines are operated by the Russian Government and the finest specimens are reserved for the Imperial Cabinet.

In the southern Urals, in the gold washings of the River Sanarka, yellow Topazes are found closely resembling those of Brazil. Associated with them are amethysts, rubies, chrysoberyls and many other precious stones. Topaz crystals of good size and color are found quite abundantly in Japan, although they have not yet been cut for gems to any extent. There are many localities in the United States where Topaz occurs, and it is often of gem quality. The group shown in the plate illustrates its occurrence at Thomas Mountain, Utah, a locality forty miles north of Sevier Lake. The crystals are found in cavities in the rock. They are never very large, but are usually clear and bright. They occur in somewhat similar fashion at Nathrop, Colorado. In the Eastern States Topaz was first found at Trumbull, Conn. It is here quite opaque and not suitable for gem purposes. Good gem Topaz has been found at Huntington and Middletown, Conn., however, and especially at Stoneham, Maine. In these localities it occurs in granite.

Of other stones which are sold under the name of Topaz the most common is the so-called Spanish or Saxon topaz. This is simply smoky quartz heated until it turns a yellow color. It can easily be distinguished from true Topaz by the properties above given.

At the present time it is also quite the common practice to vend ordinary colorless quartz under the name of Topaz. These practices are harmful to the reputation of true Topaz, as these forms of quartz are common and cheap and lack many of the desirable qualities of that stone. There is also a so-called Oriental Topaz which is a yellow form of corundum. It is heavier and harder than true Topaz, but its color and luster are not generally considered as desirable as those of that mineral. About forty years ago Topaz was quite popular as a gem and commanded three or four times its present price. At the present not more than two dollars a carat is often paid for the stone.

Topaz is often referred to by ancient writers and is mentioned in the Bible as one of the stones to be put in the ephod of the high priest; also as one of the gems worn by the King of Tyre and as forming one of the gates of the Holy City. Curiously enough, the gem referred to in these instances was the modern chrysolite, while where chrysolite is spoken of our Topaz is usually meant.

A Topaz presented by Lady Hildegarde, wife of Theodoric, Count of Holland, to a monastery in her native town, emitted at night, according to legend, a light so brilliant that in the chapel where it was kept prayers could be read at night without the aid of a light; a statement which might well be true if the monks knew the prayers by heart.

The spiritual qualities associated with Topaz are fruitfulness and faithfulness. It is also said to confer cheerfulness upon its wearer. The ancients believed that it calmed the passions and prevented bad dreams; that it discovered poison by becoming obscured when in contact with it; that it quenched the heat of boiling water, and that its powers increased and decreased with the increase and decrease of the moon. Also a Topaz held in the hand of a woman at childbirth was believed to lessen suffering. Lastly, a Topaz is the gem of the month of November:

 
“Who first comes to this world below
With drear November’s fog and snow
Should prize the topaz’s amber hue,
Emblem of friends and lovers true.”
 

Oliver Cummings Farrington.

THE BIRTH OF THE HUMMINGBIRD

 
It was born in a valley of violets
Where bird and flower for its favor vied,
Its father a poppy gone stark mad,
Its mother a reckless honey bee,
(True child of such startling pedigree)
Its cradle a sunbeam glorified.
 
 
It was bathed in a dewdrop morn by morn
And when the time for the christening came,
The font was filled with a jeweled flame;
Glitter of gems dissolved in mist,
White of diamond, its changing light,
Ruby, emerald, amethyst,
And its christening robe was encrusted quite.
 

Nelly Hart Woodworth.

THE ROSE TANAGER.
(Pyranga aestiva.)

 
“Oh, if it might be that the roses
Be winged, and flying to thee,
Could bear thee a thousand greetings, —
Thou knowing they came from me!
 
 
And if song might be given the roses,
When I sped them in token to thee,
They should warble my song to thee softly —
Thou thinking the while on me!”
 

– From the German of Abingulf Wegener.

 
The brilliant Rose Tanager,
“Encircled with poetic atmosphere,
As lark emballed by its own crystal song.”
 

might be the fulfillment of the poet’s roseate dream, and the message that he bears a vocal incense from the flower’s glowing heart.

But if the burden of the one-half of the tanager duet is “my love is like a red, red rose,” the other half probably completes the flowery simile, with the proud refrain, “my love is like a green, green leaf,” and when the time of the bloom of the rose is past and the rosy plumes, like petals, fall away, he stands revealed an olive calyx, attended as the season wanes by an assemblage of belated olivaceous buds, whose song and carmine tints are folded away to await the summons of the next year’s sun.

And when they return to us again in the full flower of their beauty from their southern home, gorgeous as if stained in the dyes of the tropic sun, their song is said to be suffused with color like the mellow tones of the rose-breasted grosbeak and oriole.

This song Nuttall describes as a strong and sonorous whistle like that of the Baltimore bird, “resembling the trill or musical shake on the fife, and is frequently repeated; while that of the female is chattering and is chiefly uttered in alarm when any person approaches the vicinity of the nest. From the similarity of her color to the foliage of the trees, she is rarely seen and is usually mute, while the loquacity and brilliancy of the male, as he flies timidly and wildly through the branches, render him a most distinguished and beautiful object.”

Audubon pronounced the usual note of this bird as unmusical, resembling the sounds “chicky-chucky-chuck,” which is not, indeed, suggestive of poetic inspiration on the part of this “poet-prophet of the spring,” but the same author states that during the spring he sings pleasantly for nearly half an hour in succession, and that the song resembles that of the red-eyed vireo, his notes being sweeter and more varied and nearly equal to those of the orchard oriole.

Mr. Ridgway describes the song as somewhat after the style of the robin, but in a firmer tone and more continued, and, as compared with that of the scarlet tanager, with which he is often confounded, it is more vigorous and delivered in a manner less faltering. He describes the note of anxiety as a peculiar “pa-chip-it-tut-tut-tut,” very different from the weaker cry of Pyranga rubra.

Mr. Chapman says the summer tanager may be easily identified, not alone by its color, but by its unique call note, a clearly enunciated “chicky-tucky-tuck.” Its song bears a general resemblance to that of the scarlet, but to some ears is much sweeter, better sustained and more musical. According to some authorities it equals the robin’s in strength, but is uttered more hurriedly, is more “wiry” and much more continued.

Of the bird of Eastern North America Mr. Maynard says: “When the cold north winds cease to blow and the air in the piny woods is redolent with the perfume of the sundew, creeping mimosa and other delicate plants, which only bloom late in the spring, the voices of the summer tanagers are heard in the tops of the highest trees, when their songs are full of wild melody in perfect keeping with their surroundings. * * * So closely do they conceal themselves in the thick foliage that were it not for the loud song notes, which are constantly repeated, it would be difficult to discover them.”

From one of its habits the Rose Tanager is known to farmers as the red bee bird, and, although a bird of day, its taste for nocturnal beetles often leads it to the pursuit of its prey until the shades of evening have darkened into night, when, with the light of its plumes extinguished, as it were, with the setting sun, it proceeds silently and invisibly upon its gustatorial mission.

But it is credible that it is only when he is in his colorless nocturnal disguise that the prosaic beetle is permitted to refresh this Avian bloom, and that when the god of day has transformed the voiceless shade of night into the winged and musical rose of ornithology for his life’s sustenance, the same moment witnesses the miracle of the “dewdrops the sunrise has reddened to wine,” and that to his inspiration is poured Aurora’s rosy libation, the enchanted

 
“Wine that Morning spills
Upon the heaven-kissing hills.”
 

Juliette A. Owen.