THE THAMES TESTING PLANT.

Auckland Star, Volume XVIII, Issue 173, 25 July 1887, Page 4

THE THAMES TESTING PLANT.

Prior to the advent of Mr J. D. Lamontthe majority of the miners working at the different mining centres on our goldfieldswere under theimpression that all the gold and silver contained in local ore occurred in the metallic form, and that the loss of bullion by the ordinary battery system of reduction was comparatively trifling. Since then nofra few of the most stubborn ones have had reason to alter their views, and the prevailing opinion now is that gold as well as silver occurs iv Upper Thames quartz in forms other than metallic, and that the battery process does not save more than 25 per cent, of the assay value of the bullion contained in the ore. At both Waihi and Karangahake stone in which there .was not acolour of gold nor a vestige of silver visible has yielded an average value of £\2O per ton by the fire test. By

way of illustrating what we mean, we append—from a record furnished to us by our Ohiuemuri correspondent of work done by Mr C. Ehodes, assayer, Bank of New Zealand, Paeroa, during the past 18 months—the results of a few assays of ore in which there was not a particle of gold or silver visible to the unaided eye, and wherein no evidence of the existence of either of the abovementioned metals, could be detected without subjecting the stone to the action of the fire :—

No. 1 sample was taken from a reef averaging 4ft in thickness in the Crown mine, Karangahake, and it gave a return equal per ton to 6660z of bullion, which on being separated proved to contain at the rate of lOoz of gold and 6560z of silver per ton. No. 2 sample came from the Rosemont mine, Waihi, and its treatment resulted in a return of 5070z 6dwt 6gr of bullion, which on being parted gave gold 320z, silver 475 oz—or at that rate per ton. No. 3 sample was obtained from a reef 3 feet thick in the Woodstock mine, Karangahake, and the following are the results at per ton obtained therefrom according to assay value:— Bullion, 2,6780z 13d\vt 8 gr; gold, 208oz sdwt; silver, 2,4700z Schvt Bgr. No. 4 sample was the product of a reef about 12 inches thick in the Adeline mine, Karangahake, and upon being subjected to the assaying process it gave a return per ton equal 6150z lodwt Bgr of bullion, which proved to be gold 4260z sdwt 4 gr ; silver, 189oz 9dwt 18gr. No. 5 sample, which was brought from the Union mine, Waihi, and was described as " barren stone," gave a bullion result at per ton of ore equal to 2490z ldvvt 16gr. This was composed as follows : — Gold, 16oz 6dwt 16gr; silver, 2320z lodwt. No. 6 sample was taken from a private claim called the Comstock, situated at Karangahake, and it yielded at the rate of 7090z of silver and a* slight trace of gold per ton. No. 7 sample was obtained by a party of prospectors who were operating on a large reef at a place called Parakawai, near the East Coast, where an auriferous belt of country was discovered about 12 months ago. This stone, when tested, gave a bullion return equal to 272 ounces per ton of ore, and of this 36 ounces proved to be gold, and the balance of 236 ounces was made up of silver. No. 8 sample was composed of tailings, being the residue of a parcel of rich ore. Treated at the Martha battery for the Silverton mine, Waihi, it gave a return equal to 282 ounces of bullion per ton, and the bullion was worth 52s per ounce.

No. 9 sample was from a reef 6ffc thick in the Imperial mine, Karangahake, and it gave a bullion return at the rate of 455 oz, 7dwt llgr per ton. When this was parted, the results were :—Gold, 260z 12dwt, llgr; silver, 4280z sdwt to the ton of ore.

Altogether, the book contains a record of three hundred assays, and the largest bullion return on the list was obtained from a sample of quartz treated for the Woodstock Company, and the bullion results of which have already besn quoted. This stone was broken out from the reef known as the Maria, and in general character and appearance it was not unlike a piece of the ordinary broken road metal, which is used for macadamising purposes.

Now we think these results will make it clear to the least skilled in mining matters that the future of the mining industry in the Auckland district at any rate and no doubt in many other parts of the colony, turns upon the . introduction of processes for the profitable treatment of refractory ores. With free milling ores, the battery process will, no doubt, notwithstanding the loss of gold, still be the most profitable, because of its cheapness; but there are mines rich in gold which cannot be worked at a profit Unless other processes are introduced. It is with the object of obtaining a plant which will prove the actual value of the varied samples of Thanie? ore, and indicate the proper method of treating it, that an effort is now being made to obtain subscriptions from the mining community; and the object is one of such importance to our whole mining industry that many who are interested in it would, we believe, be willing to sanction a small call rather than that the project should fall through. The suggestion we made some time ago that the Government might offer a bonus for the discovery |and introduction of a plant for the treatment of these ores is still worthy of consideration. But as the Minister of Mines has promised to bear half the cost of the testing plant, which will confer an immediate benefit upon our mining interests, we hope the project will not be allowed to lapse for want of a little enthusiasm and liberality expended at the proper time.