Tourmalines are also found in Moravia, the island of Elba, Sweden, Burmah, Tyrol, Canada, and the United States.
The first tourmaline deposits known in the United States were discovered at Paris, Maine, in 1820. Another wonderful deposit was found at Mt. Apatite in Maine in 1882, and up to the present time the finest tourmaline crystals have been discovered in the United States.
Really fine specimens of red, blue, or green tourmalines are uncommon and command very good prices.
Opal.
The precious or noble opal, fire opal, common opal, hydrophane, and cachelong are different varieties of a mineral that is composed of about nine parts silica and one part water.
The colors vary from chalky-white to bluish-white, from yellow to red, and from a slight play of colors to the beautiful mingling of green, blue, and red with the most remarkable kaleidoscopic effects.
The opal is 5.5 to 6 in hardness, specific gravity 2 to 2.1, lustre glassy, and translucent from a slight to a very high degree.
The opal is found in an amorphous state and never crystallizes; in fact from the condition of the pockets in which this mineral is found, the indications are that the substance was once a fluid.
Under the blow-pipe the opal loses its translucency and cracks but does not melt. Sulphuric acid will cause it to turn black, and in a cold solution of caustic potash the opal is almost entirely soluble.
The precious or noble opal is found chiefly in the mines of Czernowitza, between Kaschau and Eperies, in Hungary, and in Gracias á Dios, a province in Honduras.