Zinc ores, in the several varieties of carbonates, silicates, oxide, sulphide and sulphate of zinc, have been found in several of the Australian states, but have attracted little attention except in New South Wales, where special efforts are being made successfully to produce a high-grade zinc concentrate from the sulphide ores.
Its property of absorbing large proportions of water, up to 80%, and yet present the appearance of a hard solid body, makes the material a basis for the hydrated soaps, smooth and marbled, in which water, sulphate of soda, and other alkaline solutions, soluble silicates, fuller's earth, starch, &c. play an important and bulky part.
Tobacco is most generally cultivated on loose red soils, which are rich in clays and silicates; and sugar-cane preferably on the black and mulatto soils; but in general, contrary to prevalent suppositions, colour is no test of quality and not a very valuable guide in the setting of crops.
Land masses are denuded and minerals containing silicates are carried down to the sea as sediments.
They are silicates, usually orthosilicates, of aluminium together with alkalis (potassium, sodium, lithium, rarely rubidium and caesium), basic hydrogen, and, in some species magnesium, ferrous and ferric iron, rarely chromium, manganese and barium.