AUCKLAND OPAL MINING.

Taranaki Daily News, Volume LIV, Issue 321, 10 July 1912, Page 7

AUCKLAND OPAL MINING.

| A NEW INDUSTRY. ■BEAUTIFUL GEMS OBTAINED. It seems' probable that quite a new industry may be added to the long list which is making Auckland so prosperous—namely, mining for opals (says the local Herald).

The existence of the true gem opal at Tairua, on the eastern coast of the Hauraki Peninsula, has been known for some years, hut owing to the opal-bearing country being privately owned very little has been done in the way of developing the deposit. Quite recently, however, considerable activity has been shown in this direction. The property has been secured for mining purposes, and already a considerable quantity of high-class opals have been obtained. These have ■been submitted to some of the leading jewellers in Auckland, who report highly on their quality, some of them being of the rare black variety, and most of them being exceedingly rich in fire and brilliant coloring. The opal-bearing reef at Tairua is outcropping for a length of about 800 ft by 200 ft in width, running up to a rugged cone or cap some 150 ft above the level of the surrounding flats. Heavy opalisation can be seen ail over the rocks, and in some places the delightful reds, greens, browns, and blues scintillate in the sunlight magnificently. Apparently . almost the whole hill is opalised strata, and probably the reef continues for a considerable distance fnrtl>°r than the actual outcrops. There W a total of about 750,000 cubic yards of opal-bear-ing starta actually visible, and this quantity will take an enormous 'amount of work to handle. The rock of which the reef is formed, is a sinter containing. traces of iron. Numerous small cavities occur, and it is in these cavities that the beautiful gems exist. Wherever the iron is—in proximity to the opalisation the colors of the gems are intensely dark—deep emerald green, ruby red, purple, and a mass i of colors that change with the slightest I movement.

The gem opal is again coming into the front rank of fashion; the superstitious ideas connected' with it during the latter end of last century have gradually died out. From time immemorial opals have been great favorites. Pliny says of them: "For in them you shall see the burning lire of carbuncle, the glorious purple of the amethyst, the green sea of the emerald, all glittering together in an incredible mixture of light." Opal mining has been carried on for many years in New South Wales, chiefly in the 'White Cliffs district, and on the Queensland 'border at Lightning Ridge. The opal from the latter place is considered the finest in the world, being very often of the black variety. Specimens have realised over £4O per oz. in the rough, and one single gem was sold in Paris some years ago for £IOOO. In New South Wales the miners are not' required to keep any records of value or weight of opal won, but the Government's estimate of gems obtained prior to the end of 1908 was the huge total of £1,109,900, and the actual amount of stone handled may have far, exceeded this figure. The highest year's output was obtained in 1902, when £140,000 worth of stone was recorded. ,

In 1908 there were 400 men employed at White Cliffs, and 100 at Gemville. The White Cliffs field was. discovered,an 1889 by a hunter when tracking a wounded kangaroo. Odd bits of the gem were picked up on the surface. The main opalised strata, from which the gems are obtained, is from 20 to 35 feet deep below the level of the arid desert. Tito difficulty of obtaining water supplies was very great, and this probably has kept the field back very much. The value of opal varies greatly, but black opal is worth from £l2 per oz. upwards. iSome of the recently-mined Tairua opals have been worked into finished stones by an Auckland lapidist, and local jewellers, reporting on them, are satisfied that they have a good market value.