Copper sulphate (blue vitriol) is the most important chemical compound of copper.
The value of copper has increased within recent years, due to its enormous use in electrical work. Aside from this, copper is employed in large amount in the various alloys into which it enters, and in coins, utensils, printing plates, etc. Copper sulphate is extensively used in electrical apparatus dyes, chemical work and as an antiseptic. Large amounts of manufactured copper are exported to Europe. Smaller quantities of ores, matte and regulus are imported from Mexico, South America and other countries. Copper wire is extensively used by telephone and telegraph companies.
Diamond. See [gems].
Gems, or Precious Stones are those which, because of their beauty, hardness, and rarity, are prized for use in ornamentation, especially [110] in jewelry. The diamond, ruby, sapphire, and emerald are the only stones which are, strictly speaking, entitled to be called “precious” in this sense; but the opal, on account of its beauty, is often classed with the precious stones; as is also the pearl, which is really not a stone, but a secretion of a shellfish.
Alexandrite.—A variety of chrysoberyl found in the mica slate of the Ural mountains. It is of a rich garnet color by artificial light, by daylight of a dark moss green. It is the only stone that so changes. The finest specimens of alexandrite are nearly as valuable as diamonds.
Amethyst.—A variety of crystallized quartz of a purple or bluish-violet color, of different shades. It is much used as a jeweler’s stone. The lighter colored ones come from Brazil, the deep purple ones from Siberia. In value they are about the same as the garnet.
Beryl.—A very hard mineral of much beauty when transparent. It occurs in hexagonal prisms, commonly of a green or bluish-green color, but also yellow, pink and white. It is a silicate of aluminum and glucinum. Beryls are very rich in colors.
Bloodstone.—A green siliceous stone sprinkled with red jasper, whence the name.
Cameo.—A figure cut in stone or shell that is composed of different colored layers. The value depends on the artistic merit of the engraved figure.
Carbuncle.—A beautiful gem of a deep red color (with a mixture of scarlet), found in the East Indies. When held up to the sun it loses its deep tinge, and becomes of the color of a burning coal.