19

0,-2

During 1.917 water was used for sluicing auriferous alluvium at 198 claims, employing 61.8 persons, in Otago, Southland, and on the West Coast. The quantity of water utilized per claim varies up to about 40 cubic feet per second. Most of the sources of water-supply are privately owned, but on the West Coast and in Central Otago the Government has constructed, and now maintains, very extensive water-races for the use of miners. On the West Coast the Waimea Kumara Government water-races, in length about forty-five miles, have a capacity of 220 cubic feet per second : the cost of construction has been approximately £250,000, the value of gold obtained by use of the water being about £1,400,000. In Central Otago the Mount Ida Government water-races, in length about twenty-two miles, have a capacity of 51 cubic feet per second ; the cost of these races to the Government has been about £80,000. The water is generally sold from Government races at a charge of 2sd. per sluice-head per hour. Of recent years the cash received for water sold has been less than the cost of the upkeep of the races. During 1917 sixty-three miners were employed on claims using Government water, and gold to the value of £15,075 was obtained therefrom.* Power from water-motors is used, in the Reefton. district at the Progress Mines for milling and ore-reduction, and in Central Otago on three gold-dredges. There are three hydro-electric mining transmissions. On the Waikato River the Waihi. Goldmining Company has installed a 9,000-horse-power plant at ilorahora Falls, near Cambridge, a distance of fifty miles from the mines and reduction works at Waihi and Waikino ; the transmission pressure is 50,000 volts. The power is used for winding, air-compressors, reduction works, lighting, and other purposes. The company has the right to supply local authorities en route with power for public distribution. At Kanieri Forks, near llokitika, there is a hydro-electric power-station, formerly the property of Ross Goldfields (Limited), but recently purchased by the Kanieri Forks Power Company. The water-supply is carried by races from Lake Kanieri ; from the peltons 675 horse-power is obtainable. The transmission pressure is 24,000 volts. From the Fraser River, near Alexandra, Otago, water is taken by the Earnsclcugh Gold-mining Company for hydro-electric power for its gold-dredges, 300 electrical horse-power being utilized.

V. MINERALS OTHER THAN GOLD. Tungsten-ore. The quantity of tungsten-ore exported during (lie year amounted to 161 tons, valued at £28,972, as compared with 266 tons, valued at £19,070, in 1916. The following statement shows the quantity and value of ore exported.:

The quantity of tungsten-ore concentrate obtained (lining the year was 199 tons (value £37,863) as the result of treating 19,655 tons of scheelite-bearing quartz, from which gold to the value of £8,098 was also obtained. During the years 1914-17 inclusive, covering the period of the war, the value of scheelite concentrate produced exceeded that exported by £9,527. The price paid per unit of tungstic acid in the shipment has recently been raised from £2 15s. to £3 Bs., being double the market price ruling immediately prior to the outbreak of war. During the past year no new development of importance has occurred in this industry, although a considerable number of prospectors have been searching for scheelite-bearing lodes in Marlborough, Otago, and Southland. * For further information regarding Government water-races see Section VII (4) of this report.

Year. Quantity. Value. Year. Quantity. Value. 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 Tons, 32 51 2 39 12 17 28 55 137 68 58 £ 2,788 2,635 83 1,200 1,139 791 1,848 3,4.07 15,486 6,055 4,263 191.0 .. 1911 .. 1912 .. 1913 .. 1911 . . 1915 .. 1916 . . 191.7 .. Tons. 143 138 135 221 204 .191 266 161 £ 15,070 11,853 13,347 22,933 21,498 27,784 49,070 28,972 Totals 1,994 230,522