Part 9

Spinels are found in clay and in the sands of rivers, in East India, Hindustan, the province of Mysore, Farther India, Pegu, Ceylon, North America, Sweden, Bohemia, and Australia.

The red spinel, and especially those tints which approach the red corundum or true ruby in color, are the most valuable, and are known as ruby spinels.

Very fine specimens of ruby spinels of one carat and larger are quite rare and command good prices.

Rose-colored spinels are known as balas-rubies, pale-blue spinels as sapphirines, and the hyacinth-red, yellowish-red, and orange-yellow spinels are called rubicelles.

All these different-colored spinels, if pure and of great brilliancy, are valuable as gem stones, being only surpassed in hardness and brilliancy by the diamond and corundums.

The white spinel, which is seldom found, is sometimes confounded with the diamond, having the same specific gravity and single refraction, but as it lacks the fire and is easily scratched by the diamond, the danger of mistaking one for the other is slight. Burnt amethyst, which often resembles the spinel, is lighter and softer, while burnt topaz, although it is identical with the spinel in hardness, is somewhat lighter and possesses remarkable electric powers, becoming electric by either rubbing, heating, or pressure, and retaining electricity for upwards of twenty-four hours.

The zircon is easily distinguished from the spinel because of its much greater specific gravity. It is also doubly refractive and softer.

Garnets are softer, lack the play of color and brilliancy, and fuse easily into a light-brown or black glass.

BERYL.

The beryl is a mineral belonging to the primitive formation, and is found in quartz veins and granite.

It crystallizes in six-sided prisms and is composed largely of silica, the third most common of earth’s productions. The beryl is 7.5 to 8 in hardness, scratching quartz, but is scratched by topaz.

The specific gravity is 2.67 to 2.73, making it one of the light minerals. Its lustre is vitreous and refraction double to a slight degree; its cleavage is imperfectly basal, and it becomes electric by rubbing.

Acids do not attack the beryl, but it melts with borax and is soluble in salts of phosphorus.

This stone is found in various colors, grass-green, pale-green, light-blue, greenish-blue, greenish-yellow, yellow, and sometimes pink.

The most important of these colors is the grass-green, which forms a separate division of the beryl family, and is known as the emerald.

EMERALD.

The emerald or green beryl is one of the most highly prized of the gem stones. Its magnificent color has rightly been compared to the color of the fresh grass in spring, and in brilliancy this stone far exceeds all other green gems, excepting only the very rare green corundum or green sapphire.

The emerald is said to be very soft when first withdrawn from the mine, but it hardens by exposure to the air.

A perfect emerald of fair size is a rarity, so that the saying “an emerald without a flaw” has passed into a proverb.

This stone is so light, compared to a diamond or sapphire, that a carat emerald will be very much larger than either of the above stones.

The emerald is composed of:

Silica 68.50 Alumina 15.75 Glucina 12.50 Peroxide of iron 1. Lime 0.25 Oxide of chrome 0.30 And traces of magnesia, of lime, and of soda.

The vivid green color of the emerald is supposed to come from the oxide of chrome, as the other beryls do not contain chrome.

Emeralds are found in New Granada, near Bogota, Egypt, East India, Burmah, Ural in Europe; Salzburg, Austria; Mt. Remarkable, South Australia; and North America. Some of the finest come from the mines of Muza, near Bogota, and the best stones are called Peruvian emeralds. During the conquest of Peru by the Spaniards, many very fine emeralds were destroyed by the invaders, who tested them by grinding and pounding, and concluded that the emeralds were worthless, because they were not as hard as the diamonds or sapphires.

In 1587, Joseph D’Acosta returned to Spain with two cases of emeralds, each case weighing one hundred pounds.

Green tourmaline sometimes passes for the emerald, but it is somewhat softer and considerably heavier.

Olivines or chrysolites, if of a fine green color, sometimes resemble the emerald, but they are much heavier than the emerald and have a fatty lustre. Green spinels are heavier and harder than emeralds.

BERYL.