Another authority, speaking of this bird’s habits in the mountain regions, says, “During summer and autumn the Gray-crowned Finch is common above timber line, where it breeds, ranging higher than the titlark and being usually found in the vicinity of snow fields and the frozen lakes near the summit of the range. It is rather shy in such localities, though exceedingly tame in winter. Its flight is in undulating lines, like the crossbills. The only note I have heard it utter is a kind of churr, like the call of the scarlet tanager. They stay above timber-line till the close of October or the middle of November. They are perpetually roving from place to place feeding upon the seeds of weeds and grasses and are never at rest for a moment at a time, constantly whirling about in close, dense masses, like so many longspurs.”
GRAY-CROWNED LEUCOSTICTE.
(Leucosticte tephrocotis).
Life-size.
FROM COL. CHI. ACAD. SCIENCES.
CORUNDUM AND SPINEL.
CORUNDUM.
The mineral species Corundum affords a number of gems known by different names. These differences arise from the fact that the stones were used as gems before their mineralogical identity was discovered. Thus red Corundum is known as the ruby and blue Corundum as the sapphire. When Corundum suitable for gem purposes occurs of other colors, such as green, yellow or violet, the gems are sometimes known as green, yellow or violet sapphires, respectively, or by the name of another gem which they closely resemble in color, with the adjective Oriental prefixed. Such are the gems known as Oriental topaz, Oriental emerald, Oriental aquamarine, Oriental hyacinth, Oriental amethyst and Oriental chrysolite. Colorless Corundum is known as leucosapphire. While Corundum of all colors is used for gems, it is only that which is transparent which can be so employed. This is sometimes called noble Corundum to distinguish it from common Corundum. The two, however, often occur together. Common Corundum is used as an abrasive, emery being one of its varieties, but it has no gem value.
Corundum is a sesquioxide of aluminum, with the percentages aluminum 53.2, oxygen 46.8. Its hardness is 9 in the scale of which diamond is 10, and no other mineral except the latter equals it in hardness. This hardness gives it a wearing quality as a gem second only to the diamond. The varieties of Corundum differ slightly in hardness, sapphire being the hardest. Noble Corundum has a brilliant, vitreous luster, which, while not equal to that of the diamond, is superior to that exhibited by almost any other gem. Corundum is a heavy mineral, its specific gravity being four times that of water. This high specific gravity affords an easy means of distinguishing the gems of Corundum from those of other species. Corundum is infusible and is not attacked by acids. It crystallizes in the rhombohedral division of the hexagonal system, certain crystal forms being characteristic of the two varieties, ruby and sapphire. Thus ruby tends to crystallize in flat rhombohedral crystals, while sapphire generally forms in longer, hexagonal prisms. (See colored plate in November number.) Corundum is doubly refracting and dichroic. Of the different colors of Corundum above referred to, the blue or sapphire is most common, the red or ruby next. The other colors occur rather sparingly, green having been almost unknown until the discovery of the Montana sapphires. The nature of the coloring ingredient of the different varieties of Corundum is not known, but there is some reason for believing it to be chromium, for Fremy obtained artificial red and blue Corundum by mixing chromium with his other ingredients, after many attempts to obtain the desired color had failed.
Red Corundum varies in hue from rose to deep red. That of the latter tint is the true ruby, the color known as pigeon’s blood being most highly prized. Faultless stones of this color have long been the most valuable of gems, exceeding the diamond in price, weight for weight, unless the latter is colored. Rubies above three carats in weight are about ten times more valuable than ordinary diamonds of the corresponding weights. But few rubies exceeding ten carats are known. The King of Pegu is reported to have one the size of a hen’s egg, but as no one has ever seen it the story may well be doubted. In the crown of the Empress Catherine was, however, one the size of a pigeon’s egg. There is also a large uncut ruby in the British crown, which Ruskin calls the loveliest precious stone of which he has any knowledge.
The chief home of the ruby is Burmah. From its mines and those of Siam and Ceylon have come practically all the world’s supply of rubies. The most important Burmese mines are in Mogouk, ninety miles north of Mandalay. The rubies were evidently formed in limestone, which is now much decomposed, and seem to have been the result of metamorphism of the limestone by the entrance of eruptive rocks. The ruby-bearing earth is known as “byon,” and the stones are obtained from it by washing. The rubies are usually in the form of more or less complete crystals. The mines have been worked since the British occupation of Burmah in 1886 by a British company, and there can be little doubt that a desire to acquire these mines was the chief reason for the occupation. The mines have not proved very profitable, however, and only within the last year or two has the company been able to pay any dividends. The hope of success has lain in the introduction of machinery for washing the byon more cheaply than it could be done by the primitive native methods, and it is now believed by the introduction of an electrical power plant that this has been accomplished. This company now produces at least one-half the annual yield of rubies of the world.
Previous to the English working of the mines the ruby mining was performed by local miners under control of the native government, all rubies above a certain size going to the king. Whenever a ruby of unusual size was found a procession of grandees, with soldiers and elephants, was sent out to meet it. One of the titles of the King of Burmah was Lord of the Rubies.