Topaz (25c) in its clear varieties is one of the precious stones. The crystals from the Urulga river, Siberia, are remarkably fine, and of a delicate brown colour; they are kept covered, as the action of light slowly bleaches them. The yellow crystals from Brazil assume a peculiar pink colour when heated, and are then known to jewellers as Burnt or Pink Topaz. A fine orange-red crystal from Brazil is exhibited. Garnet also belongs to the group of precious stones; when the red is tinged with violet, the stone is the Almandine or Syrian Garnet (named after Syriam in Pegu), and when cut _en cabochon_, the Carbuncle of jewellery (26f); the Cinnamon-stone or Hessonite varies in tint from hyacinth-red to honey-yellow (26e); the Pyrope, including the “Cape Ruby” and the Bohemian garnet, is blood-red (26e), Demantoid is an emerald-green (26g). Jadeite (27a) is one of the green stones which, under the name of Jade, are wrought into ornaments in China: from jade it is distinguished by its chemical composition, structure, and higher specific gravity. Among the specimens of Epidote (27c) a remarkable series from the Untersulzbachthal, Austria, is exhibited. Mica (28a) is the name given to a group of minerals differing much from each other in chemical composition and optical properties, but having as a common character an easy splitting, or cleavage, in a single direction, and thus affording plates remarkably thin, transparent, tough, and elastic. One of these minerals, Muscovite (28d), has been used in Russia in place of glass for windows, and is now in common use for lanterns and stoves, not being so easily cracked as glass by changes of temperature; it is often known in commerce as talc, a term restricted by mineralogists to a different mineral. The group of Felspars, the most important of the rock-forming minerals, begins at case 28f. After the Felspars comes Beryl, of which the bright green variety, Emerald (29c), is one of the most valued of precious stones. It was in ancient times worked in Egypt, as is proved by specimens found in the old workings by Sir Gardner Wilkinson, and presented by him to the Museum. Emeralds occur in the Urals; but the locality for the finest stones has long been Muzo, about seventy miles from Santa Fé de Bogotá, in South America. Faceted specimens of the colourless Beryl, of the bluish-green Beryl, known in jewellery as Aquamarine, and of pink Beryl from California and Madagascar, are exhibited (30a). In cases 30f to 32d will be found examples of the Zeolite group of minerals.