The Encyclopedia Americana (1920)/Sapphire

SAPPHIRE, a mineralogical name including all highly colored and transparent varieties of corundum (q.v.), except the red, which is called ruby, an exception confined chiefly to jewelers. Sapphire corundum occurs in three forms — as small, distinct crystals, hexagonal or rhombohedral in various modifications; as transparent portions of ordinary corundum; and at times as nodules or small rounded masses enclosed in ordinary corundum, though distinct. Most gem sapphires are of the first kind; but some fine stones have been cut from material of the two latter kinds, especially in the corundum workings in North Carolina, notably the Culsagee mine in Macon County. Sapphires present almost every variety of color, although blue is the most familiar, deep shades being most valued. Other blue gems occasionally seen are blue tourmaline (called Brazilian sapphire), cyanite and iolite, which is known somewhat as water-sapphire. True sapphires are, however, easily distinguished by their greater hardness (9), and density (3.95 to 4.1). The main sources of sapphire are Ceylon, Cashmere and the Pailin district of Siam, also the Anakie district of Queensland, Australia. In the United States, sapphires are obtained chiefly in Montana; first from the “bars” or low bluffs, of gold-bearing gravel, along the Upper Missouri River, east of Helena and later from a decomposed igneous dike at Yogo Gulch, in Fergus County; also at Rock Creek, Granite County and Dry Cottonwood Creek, Deer Lodge County. The river bars and Rock Creek yield a great variety of rich and delicate colors, as in Queensland, but Yogo Gulch furnishes the deep blue shades most valued and is being worked very extensively. Small and poorly colored stones are largely sold for watch-jewels. All blue and green sapphires, like rubies, possess marked dichroism, a point important to the lapidary, as the tint of gems from such crystals depends upon the direction in which they are cut. In biblical history the sapphire was a stone of an azure color (Exod. xxiv, 10) and very precious (Job xxviii, 16). It was the second stone in the second row of the high priest's breastplate, which is now believed to have been the lapis lazuli, and not the modern sapphire, as doubtless was also the stone mentioned in Rev. xxi, 19. Among the Greeks the sapphire was sacred to Jupiter. See Precious Stones.