Page:Downey•Quartz·Reefs·West·Coast•1928.pdf/29



This field was about seven miles south from the Town of Collingwood, near the eastern boundary of Aorere Survey District. Auriferous reef was first found there by Thomas Adams and party in 1866, in a belt of graphitic phyllites and crystalline schists. This party worked their find for about two years, during which they are said to have won gold to the value of £1,500 merely by breaking up with hammers the gossan forming the outcrop and washing the gold by hand from the crushed material. In 1869 a company known as the Perseverance was formed in Nelson by Mr. James Bennett to work the reef. This company erected a battery in the neighbourhood, and systematically operated the mine till 1876, when it ceased work. No exact figures are available dealing with the tonnage of stone crushed during these years, but it is estimated that about 8,300 oz. of gold were won, and the average value of the ore is said to have been about 10 dwt. gold per ton. Three years later, in 1879, another company, known as the Johnstone’s United, was formed to give the property a further trial. This company erected a battery in Wakefield Gully, and worked the mine continuously for the following fifteen years. The data regarding the crushings and yield for this period are, unfortunately, as scanty as for that during which the previous company carried on its operations. It is known, however, that for the years 1893-96 inclusive 14,463 tons were treated for a yield of 2,893 oz. gold. Further figures published in the statement of affairs of mining companies in 1906 show that a total of 10,439 oz. gold had been won by the Johnstone’s United Company up to that year. This would mean that during the period 1879-92 the gold recovered must have amounted to 7,546 oz.; and, as the ore crushed during these years seems to have averaged about 5 dwt. gold per ton, it may be estimated that in order to win this gold about 31,184 tons of quartz must have been crushed. The whole output of the mine, from the time it was first opened till it finally closed down in 1896, may be approximated at 61,259 tons of quartz, which yielded 18,745 oz. gold, valued at about £72,282. The mine was, however, at no time a profitable one, the total dividends paid only amounting to £1,916.

The reef was of lenticular character, and varied in width from 18 in. to 15 ft., the average width being about 3ft. J. M. Bell has shown that, as it was followed down, three distinct zones of values were revealed. At the surface, and for a considerable distance down, the reef was a gossan of a rusty-grey, porous nature, portions of which were highly auriferous. Below the gossan was a sulphide zone, containing splashes of granular pyrites, galena, and sphalerite, portions of which were also fairly rich, carrying up to 2 oz. and 3 oz. gold per ton. Below the sulphide zone was a third one in which pyrites occurred, but none of the other sulphides mentioned. This zone was poor in gold values. Near the surface the reef lay in an almost horizontal position, and was worked in a manner resembling longwall in a coal-mine. The travelling roads were taken in alongside the solid quartz, no filling being used to hold the hanging-wall, consequently the openings, which were up to a chain in width, became very dangerous, and officials of the Mines Department had to insist on better stoping methods being adopted. As depth was attained the reef was at intervals stepped down by more or less vertical faults, and where these steps