Ultramarine Lazulite Lapis Lazuli, or Blue Spar, a mineral distinguished for its beautiful azure-blue color, highly esteemed as an ornamental stone. It is commonly obtained of massive form, and of compact or granular structure. Crystals, which are rare, are 12-sided; a fine specimen of the regular dodecahedron with mirror-like faces is contained in the collection of the French school of mines. The mineral is a silicate of soda, lime, and alumina, with a sulphide, probably of iron and sodium. The analyses give variable results. That by Clement and Desormes, the first of those below, is regarded as giving the true composition; by following it, artificial ultramarine, a pigment formerly prepared directly from the mineral, has been successfully manufactured. The fourth, by Varrentrapp, is of an artificial ultramarine. The second analysis is by Klaproth, and the third by Varrentrapp, as given by Dufrenoy (Mineralogie):

The hardness of the mineral is 5.5; specific gravity 2.38, crystals 2.959. When melted by the blowpipe it loses its blue color; but a variety from Chili recovers it on cooling after calcination. Lapis lazuli occurs in calcareous rocks, associated and sometimes mixed with mica and iron pyrites. It is brought from Persia, China, Lake Baikal in Siberia, Bokhara, and recently from Chili and California. In trade it is known as the Armenian stone. The principal use of the stone has been for making the blue ultramarine pigment; and as from the best stone only 2 to 3 Per cent. can be obtained, the cost of the purest article is sometimes over $100 an ounce. The artificial preparations, however, are now very generally substituted. (See Ultramarine.) Lapis lazuli was employed by the ancient gem engravers, and the fine specimens have ranked among choice jewels. The stones through which the mineral is disseminated are carved into many ornamental objects, as vases, snuff boxes, cups, and even architectural ornaments. In the Orloff palace at St. Petersburg are apartments lined with lapis lazuli.

Imitations of it are made of bone ashes colored with oxide of cobalt.