In Rhenish Prussia, zinc ore (smithsonite) deposits are found in strata of Devonian age. These deposits are approaching exhaustion. The chief zinc deposits of Westphalia are in Devonian strata. The historic mines at Freiberg (Erzgebirge), in Saxony, produce a small quantity of blende from the concentration of galena ores. The blende carries considerable iron and silver and some of it contains traces of tin. These mines are controlled by the Saxon government.
A considerable quantity of blende ore is concentrated as a by-product in the dressing of the lead ore of the Upper Harz, Hanover. The ore of Rammelsberg, in the Lower Harz, occurs in a bed interstratified with lower Devonian slates and sandstones; it is an intimate mixture of blende, galena, pyrite, chalcopyrite, and barite and some calcite and quartz. Zinc is produced as a by-product of lead ores in the valley of Lahn (Nassau), where a series of strong veins are found in Lower Devonian strata.
Australia.
—The zinc resources of the Commonwealth of Australia are chiefly in New South Wales and Tasmania. The former has been the chief source of zinc in the past, but the Tasmania deposits are now being rapidly developed and equipped for production.
The most important source of zinc ore in New South Wales is the great Broken Hill lode, where operations began in 1884. The country rock comprises crystalline schists and gneisses. Between the oxidized and primary sulphide ores was a thin zone of secondary sulphides. The early operations in the district were for lead, and immense dumps accumulated of zinc-bearing ores sorted out or of zinc-bearing tailings from the concentration of the lead ores. In 1903 these dumps were estimated at 5,687,400 tons carrying 18.6 per cent. zinc. With the development of demand for zinc sulphide ores and of oil flotation methods of separation and concentration these dumps became important sources of zinc concentrates, but many of them are approaching exhaustion. The sulphide ores are a close mixture of galena and zinc blende, carrying silver. There are two classes of these ores, distinguished as silicate-gangue ore, and calcite-gangue ore. The silicate gangue ore bodies carry rhodonite, garnet and quartz and are richer in zinc and silver than those of calcite gangue.
Eight mining companies are now at work. In the order of the importance of their output and ore reserves, these companies are: Broken Hill South Silver Mining Co.; Broken Hill North Mining Co.; Zinc Corporation; Sulphide Corporation; British Broken Hill Proprietary Co.; Broken Hill Proprietary Co., Block 10; and Broken Hill Proprietary Co., Block 14. The estimated ore reserves of all the mines approximate 12,000,000 tons.
The Broken Hill South Silver Mining Co. has ore reserves estimated at 3,350,000 tons, and is the largest producer. Broken Hill North, Amalgamated Zinc (de Bavay), Zinc Corporation, and Barrier South Ltd. are controlled by Govett and associates, a group of Australian capitalists. The Amalgamated Zinc Co. in 1913 treated 498,289 tons of tailings, obtaining 140,098 tons zinc concentrates, carrying zinc, 48.9 per cent.; also lead concentrates amounting to 1,584 tons, carrying 57.1 per cent. lead. The Zinc Corporation, a company formed by Bewick, Moreing Co., has ore reserves estimated at 1,504,211 tons, averaging 14.8 per cent. lead, 9.2 per cent. zinc, and 2.5 ounces of silver per ton. The mine of the Broken Hill Proprietary Co. is, according to last reports, nearly exhausted.
The principal deposits of Tasmania are those of the Primrose, Hercules, and Tasmania Copper Mines, all owned by the Mount Reed Rosebery Co., affiliated with the Mount Lyell Mining & Railway Co. The state geological staff estimates reserves at 1,272,500 tons averaging 29.79 per cent. zinc, 8.89 per cent. lead, 12.16 ounces of silver and 0.17 ounces of gold per ton.
Italy.
—The zinc production of Italy is derived from the Iglesias district of Sardinia, and the Province of Bergamo. The Iglesias district is in the southeastern part of the island of Sardinia. The ores are oxidized and mostly worked by open pits. They are mined and milled by two Italian companies, Societa di Monteponi, and the Societa di Pertusola. The ores have usually been smelted in Germany, England or Belgium. The Bergamo mines, in the Province of Lombardy, are worked by the English Crown Spelter Co., which ships the ore to Swansea, Wales, for smelting.