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.

[Illustration: TOPAZ.]

Left column:

Topaz with Mica and Feldspar (Russia.)

Topaz (Brazil.)

Center:

Topaz in Rhyolite (Utah.)

Right column:

Topaz (Japan.)

Waterworn Topaz (Brazil.)—Loaned by Foote Mineral Co.

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.