HAURAKI GOLDFIELDS.

Auckland Star, Volume XLV, Issue 166, 14 July 1914, Page 7

HAURAKI GOLDFIELDS.

GREAT POSSIBILITIES FORECAST. ATTENTION TO THE BASER METALS. (By JM>. AIILLER, M.E.) I That these goldfields. which have had, jin a sense, a somewhat short-lived his- ! tory. are bound soon again to occupy the attention of the mining public goes without saying, for. it seems patent to most people who have studied the matter, their present moribund condition cannot be attributed to their exhaustion. One must look to other causes for the momentary abandonment of fields from the surface of which so much wealth ha,s been won. In looking at the evolution of such mining countries as Saxony. Mexico, California, etc.. one can trace periods of great prosperity, which, however, became retrogressive for -.1 time until, with the advent of more scientific methods and the application of very much more capital the mines boomed again, to fall off once more with the exhaustion of the deposits, or some radical change in the physical conditions which rendered the operations unprofitable. In the mining chronology ol every country we tind history repeating itself. At first only those were handled where the precious metals existed in the metallic, or native, state. When once the ore did not yield to the then known methods of extraction it -was abandoned as refractory or rebellious. With the advance of technical education intractable ores became quite "docile." and at the present moment nowhere is ore to be found whirti cannot be made -t<> yield its valuable contents. Here in New Zealnnd projectors look askance at anything which does not contain the precious i metals in the free state, while in many parts of Mexico, where mining has been carried on since early in the sixteenth century, the appearance of virgin silver in a vein indicates to experienced miners the vein is about to "peter out"! In California only free-milling ores were searched for and lwndled. and it was when these became exhausted that attention was drawn tn other minerals in which the precious metals existed, but which required a higher degree of skill to render them marketable. Then, mining in all its branches became more scientific, more capital was sunk in tlie ventures, and the business became more permanent aud lucrative in character. All men know ore is irropkicahle. We sow and reap where the same thing was done thousands of years ago. but every ■ton of ore taken from a mine means one ] ton less; it cannot lie replaced. In| most civilised countries the extraction of -metals is carried on: gold, silver, copper, lead. etc.. are largely produced all over the world, while here in NewZealand. Where all of those metals occur, all and almost every attempt to render their extraction, when in combination. <an economic success has been characterised 'by failure! Cold, and | gold only, has occupied the attention of mining adventurers, while almost everything else, no matter valuable it might be considered in other countries, has been recognised as outside the pale of the ordinary prospector's experience, or beyond the capacity flf the local | metallurgist. As soon as it was found! the gold "didn't go down": that is to Bay. when its mineralogical character changed, ihe prospect was abandoned, and pastures new were sought by those who wrc accustomed to "colours." and to cjloi'.iS only. Copper or lead ores, irrespective of what other valuaible ingredients they may contain, were, and ore. looked upon as of no value, until today the industry ha- fallen one might almost say into a »ta.te of collapse. The rich patches in Coromandel were soon exhausted, though followed down about 400 ft. where, so .soon as the ore changed in constitution the "show" wa.s abandon-.-d. This applies to many other place, in this country, where anything Uia-. was not free milling was looked j upon as something to be avoided. In other countries people recognise the necessity for modifying the treatment to suit the altered conditions as depth was attained. To prove this, one has but to siinlv the development of mining and metallurgical appliances in the C.S.A. to become convinced of the fertility of the American mind in adapting machinery and methods to suit the environment or change in constitution of' the material to lie handled. Tlie question ot the labour costs as between the! two countries is of so very much moment, as some imagine. Tor tne poorer the ore tbe higher the grade of skill required in its treatment. Cheap labour is as a rule poor labour. For instance, we know- of low-grade propositions in Mexico which, with native labour at Idol. |Mex.). i.e.. 2/. per day. could not be made profitable, but, in the hands of skilled foreign miners, receiving 21dol« gold for the same time. h.mdVome returns were obtained. in Huelva. .s pa i n copper ores could not be treated although the workers Teeeive'd 2/ or so daily. The same material is now shipped to England, where it i*. profitably reduced. I n Austria all ores containing anything of value are put to use. so that no mine containing anvthmg of value, no matter what its character may be, fa allowed to lie idle There capital and skill can be found as elsewhere, for almost any mmm" venture, while here almost everything else but free gold j* avoided. Ir an attempt should he made to open np a property the capital subscribed is ac a rule, "rowdy inadequate to the requirements of the business. There are in i*iis country lead and; copper mine* standing idde. all containing some- gold and silver, which would elsewhere dud ready purchases. IN„ doubt much disappointment was felt by investors, who were advised to adopt expensive ma . ohinery and methods, which could l«ad to failure only, but «iis applies to aU countries where mining fc carried on, and is no rejuson- why such richer should remain unutilised. iR-efcTenco in sometimes made to the great distance lyin" between New Zealand' and the principal markets for mentis and minerals, but Whvn one considere' liow great is the trade between, say. Peru and England, in ores and concentrates, and the many mites the material (has to bo packed from the sierras to the coast, this objection is- valueless. IMcor. people ore aware of the value of gold and silver, but how many kmrw that every per cent of coppv-r is about equal •io'.ld.wts of gold, or every per cent of lead jdwts of the yellow metal? As these ores contain here a certain amount of gold and silver, all of wiiah can be recovered by concentration, owners of land* whereon these mineral* arm found do themselves an injustice in not puttin-' them to a good use.

.At Coromandtel and! the Thames, where such, large quantities of gold were recovered, -the working of the mines iha« (become "smaller -by degrete and beautifully ]es6." Not because the precious nictate no longer-cxiet, but because the

mineral has- -beiccmie more refractory as depth wasi attained, and the -'old* uee and wont" method's are no lomger applicable. 'At Mt. MoTgan, in Queensland, the gold was. so tine it had to be treated by chlorination, and .-us depth was attained this process wae no longer applicable. (But the mine was not, in conisequen'ce. abandoned; different and more scientific methods were applied, so tbhat the ropperwUiich'h'ad crept- in as depth wais reached became a factor as important, if not more co, than the gold itself. So it was at iP»rcken Bill, X.S.W., a good many year* ago. where the ore. cflfibonate of lead, containing silver, ran in the furnaces like water, and it was for a long time the richest mine of its ■kind in the. world. When water level was reaahed. that is. the point where oxidation has ceased (not where water is met with) a good deal of the ore became more base and richer in zinc. All who have 'had l 'to do with such ores know what difficulties, arise through the presence of the latter metal. Still, the proprietors did not abandon riie property: they simply adapted new mrthods to the altered conditions, and the zinc, from being an imatbus. bus become a valuable asset. In some parts of the JTau-riki field tlie everincreasing presence of surphurns. as the mineral is called, permits of a rocovery of not over 35-50 per cent of the assay value, hence the necessity for our having a correct solution of this allimportant question. According to Peters, "a large quantity of the ore values of the world are contained in ores of this description, wliile the mining districts of I'.SJA. ami Mexico are studdwl with ores of this kind, many univorkc.l. and marry workable, under proper conditions.-" At. Te Arolha, where there is much mineral nf a lyase or refractory character, many attempts have been made to solve the problem, but without effect. Patent furnaces were adopted at the instigation of metallurgical experts, and; now around some of the mines old weed overgrown plant ir. to be seen putting one in mind of Panama after the departure of <le Ix-sscp-s! >im-e thit-e failures took pl-rtee vas>t improvements Clave been made in the methods of ore treatment, so that if once people here could' be convinced those pyritic on* contain much latent 'wealth, place* now almost dxiserted! may become again "The busy haunts of men." (To be continued.)