Tourmaline (33a), when free from flaws, is, in some of its varieties, to be classed with the precious stones; among these being a pink variety called Rubellite. Fine specimens of Rubellite from Burma, the Urals, and Madagascar, are shown in the case; one specimen from Burma, poor in colour but remarkable for its size and shape, was brought home by Colonel Symes, to whom it had been presented by the King of Ava in the year 1795. The pink-and-green tourmalines from Maine, U.S.A., and the magnificent crystals from San Diego Co., California, are among the more beautiful of the mineral products of the United States. Examples of the blue Tourmaline, or Indicolite, are shown in case 33b. A rich blue mineral, the Lapis-lazuli of jewellery (34b), brought from Persia, Siberia, Bokhara, and Chili, is a mixture of various species. When powdered, Lapis-lazuli furnished the once costly pigment ultramarine; but by the discovery of a method of producing an artificial and cheap form of the latter, the use of the mineral as a pigment has ceased. [Sidenote: Sulphates, Phosphates, etc.] The sulphates of Strontium, Celestite (35c), of Barium, Barytes or Heavy Spar (36a), and of Lead, Anglesite (36e), are all represented by series of specimens. Gypsum, or Selenite (36f), is a hydrated sulphate of the metal Calcium: when heated, it gives up its water of crystallisation and falls to a white powder, known as “Plaster of Paris,” which, when moistened, again combines with water and yields a coherent solid. Gypseous Alabaster, a massive variety of Gypsum (36h), owing to its whiteness, fine texture, and softness is used as a material for statuettes and other indoor ornaments. Oriental Alabaster is a harder substance, Stalagmitic Calcite, carbonate of Calcium. Borax (37c), a borate of Sodium, is much used as a flux, also in soldering, and in the preparation of easily fusible enamels. It was formerly carried over the Himalayas on sheep and goats from lakes in Tibet, but is now obtained largely from the Borax-lakes of the United States, and is also extensively prepared from the boracic acid lagoons in Tuscany. Nitratine or Soda-nitre (37d), found in Chili in beds of large extent, is largely used for the preparation of Nitric Acid and Saltpetre, and is also used as a fertiliser. Calaite or Turquoise (38g), a phosphate of the metals Aluminium and Copper, is generally massive; only very rarely does it occur in the crystalline state. Being as hard as Felspar and taking a good polish, it has been much prized in jewellery; that which comes into the market is chiefly brought from the Turquoise-mines not far from Nishapur, in Persia. [Sidenote: Amber.]