Surveys-Geological and Otherwise.

Thames Star, Volume XLVII, Issue 10852, 29 April 1911, Page 5 (Supplement)

Surveys-Geological and Otherwise.

In dealing further with Thames geology, ono would have expected

that the very important factor of the

dynamics of faults andl slides would hava been deilt with in a thorough manneir. This subject has been dismissed (l:ry thel simple population or asiaumption of the position of the Moaivataiai-i fault at 1000 ft, as projected dbwhwaircls biy Mr EL F. Adams. Tlte arsumption has been held that tha fault would comtinuei downwards at an avea-ag.e dip of iocleg 1., the position of ths fault has 'Lscn shown and the various retfs plotted ait this

level. If the Mk>aiuitaiai'i fault continues downwards unifo.rmly to 1000 ft, as shown, then it will remain the exception .\u far as miningl geology is' concern :d. When tho physical nature of Tlucaes field is,.taiken into CMnsidera•tioii, it is to Lie expected that the a.njifl'D of dip will ba veiy much loss than 45dei>\, in fact, as".tli.es .slide approaches ti!;-i west, tiO-wards the deeper waters of the Firth of Thames, a tfery ciiMis'idt'ira.ble flattening would almost inevitably occur, owing to the hit?n-al thrust," to the west," of the mast-i of rock that hius 'been diislocated tlu-DUgh faults' agency.

I hava not been aHo to see any reference to tlisi known fact of . the fault having 1 Lem iiiter'sertecl in, the 640 ft level of tliei Caledbnian mine.

believe that as prospecting wtts 1 proceeding; at this level the slide or fault was out through, with all of the chaVacteristicg at all events, of the main fault, and at a point very lmrch to the wesrtliv«.rd of its calculated distance, on the; 45<lb?'. angle presumption. However tliia mia} r life, it h .strange- that the dynamics' of faults has not received nnicOi more attention than that bestowed upon the subject in the* Thames Bulletin.

The fact that the Cbmstock. lode hay so frequently been referred to as a cTini-terpart of the Thames field : should, in itself have been considered of sufficient importance to> have jostifieid th<? pushing of the analogy to its logical conclusion.

As a matter of fact, tho l'icih brn;m7as of the Ctamstock, which ccnv in formation somewhat identidal witli Thames ore bodies, were considered of no importance after a certain zone had <l:.«eiern passed through, and, in consequencei, work was abandoned for many years ; latterly, -however, work has beien prosecuted with something like a system at a depth of 2300 ft, with the result that ore from £20 to £30 pcn 1 ton Jiafe ■ibeeii located, and of very conaidei-aMe extent; such reresults or similar 1 results, by analogy, are, to Ua ' anticipated . a* Thanies.: but., instead of tilie officers of tlie SVurvey holding out aai,y hopes of sunh a condkion of affairs, they have dismissed the I,OfK'ft> cn'osscut with noitbingl but passing mention. The fact that every leader yet intersected in thisi crosscut, being of a, promising

and gold-bearing nature,'should havfe been ai gii-ida to those whose duty it was to give due importance to these vtery important features, and the c:nuplex lninieralogical characteristics of ■the ores themselves.

This metallurgical treatment of ■these oitea and tlile economic; requirements of such, processes, is of vital importance to! the Thames! field!, and special attention should have be:n restarted upon this important matter. There is no question ailioufc the metallurgical practice of Thames being hopelessly arid absolutely out of date), and it "may 'ho taken as established, thajti, unless the practice is brought into line with the requirements of the. ores themselves, the Thames -will always keelp up its -reputation foi( small percentage recoveries and enoi'mo'usi losses in its obsolete and fossilized plants.

Ai passiing reference has b?ietn made in the Bulletin to the only modern plant that was erected on the field. I allwfe to the. staeilteire ait, Waiomo.. This is no place to discuss the policy of the directorate which was such that a closing down was rendered inevitable. It waa r.ot, closed down on account of thet unsuitaibilitty of the ores for treatment fay that process, which I hiadl outlined and recommended, it waa owing to the fact -that the full i scheme of development, work was not daiT'ied otut, The writer of the Bulletin hafc disposed of this important subject in two- paragraphs and has stated tha,t the smelting capacity of tho plant Was 250 tons per day, as o matter-of fact the furnace! was 100 per dlay, and the alignment tli.at its. capacity Was 250 tons was used to demonstrate, to tha author's! satisfaction, that it could never be supplied with ore» to keep it limning.

If either mining doanmtmi-tics were satisfied with picking- the eyes out. of their minieis, in the same mannei' that is adopted at Thames! suuli Cbromandel", ii> is quest ion aibl.e wlietlu.-r then." would' Tw a dozen largo smelting works im existence. The fa* thait the smelter in question produced matte' from an o<re tha.t liiairll beiaii consistently Condemned % all the metallurgical esyierts of the Departme^nti and by tho "Old Hands, of thei Tlvamc^"' ml particular, proves that it is^ailvcmt timo that the mmmo 1 coimnnmities of New Zealand, and the ecionomie ppolos'iciul staff of the D'oniinion, should ailtesr their metlicds, if they can, and

maike bonia effort to bring their practice into line with that, which exist:

elsewhere, instead of standing idl;

by and demonstrating, by their masterly inactivity ,to the metallurgical woridl at large, that they are hopelessly incompetent tot deal with problems that lie at their very doors.

The matte that was. produced by tho albove smciter, in addition to a high tenour in copper, was of exceptional value in gold and silver, and I was informed, whilst in Sydney, alkmt 15 months .ago, that the value was higher than any matte that they had handled for yearn

It was not to by expected that the development of the large ore bodies in tha vicinity of Thames could Ix 3 carried out without a. large amount of capital! Primarily it Was owing to ■tha dcimmatory reports of the mining people, _ Including: the officer of tho Economic! Geological Survey, and tli'o resistance; to innovations, in the form of new metallurgicial methods, that this very lacik of support oefcurr'ed, and it does net appear to be wry likely tint any great advance in finaucn will occur in these fields aa long as th-j Bulletins, which- are is&ued under the authority and with the hall mark of the Mines Department attached -to them..

C'onsidVring that in eiveiy every, to date, the various authors liivve consistently dlaminted what, through their mining and metallurgical expenienco they could not account for, it iy not likely that capitalists ai Je going to be incl'iieecl to assist.

'While on ilio subject of Thames mmiii"' it c|3ii-tainly seems remarkabla that the largla ore bodies of the field should! ibta tuiliied down as. unpayable u.neT worthless without ajiy data as to what constitutes, an unpayable miiifl teing submitted to> the public it, ia also strange that the author has not gone into the- etruomio conditions which exist, to prove that they are so different from wkait occur elsewhere, as to preclude- the possibility of miningl and milling of low omulo O'ie bodies! 'being profitable?'

The- Thames field is virtually a daylight gloldlleld. Nearly tho whole 'if the mines, excepting! those occurring on the flat, have 'been, and can still 'be, wtoriketl; wlater frte for many yea.rs : even those on tho flat cany a mere trifle of water compared with many other mining* centre®. Firewood, coial, mine timbcn-, and lalxvur at(\ cihcapei', or as cheap, aa in S'coree of otliei- centres. Transport- facilities and climatic conditions are exceptionally favourable;. Wherein 'iocs Iho difficulty lay?

It. cannot 'be said that the ores themselves present' insuperable difficulties; in the way of treatment. Of course there may te said far Thames that, with one exception, the milling methods that are applied to the; mineralised ores are the same as those that .were in use. in the initial stagies of the field!!. Even 20' year's after the' commencement of thu field thdS practice at tho mills was such a,s to rail foi' the miost drastic clriticism owing 1 to tho phenomenally low recovery of values! If this held good 20 years after the first outbreak of the field! to what extent w'ouldl the same criticism apply to-day? It -would have been Ttei°y much .morio in order and within the scope or "the Bbonorinc- Geological staff's woirlij had they dealt with problems j/ucih as these, and enlightened the mining' community as to' their remedies for same.

Sl>>me as^;\y.-3 t are given in the Bulletin, extending from 2.2s to 12s ponton, cno set only, I think. If this set of assays is representative of the bulk of tho reefs... then it appears, ontha fa,cio of it, to bo payable. If, on the other hand, the assays given are not representative, then they should hiivio found no place in the report at all! It would 'en; interesting to know why the. great number of assays that wero taken were not published, as

the qioljcstuMi of the. payability of an ui-o body or otherwise depends, entirely upon tho ■ uipaibiliiy and experience of mining cnig;n"era to determine it. AI dictum laid down by an officer of tho staff, whora expeiieaice in these matteis is evidently no qualification, is not to be :uxepted by tha minintx aoinnnunity "wit!ioi.it tho support of much fuller ewidtuce than that now sulbmittel.

In order to show what grade of mine may be made to. pay I would submit the following! particulars. In Bbmcligo, Victoria,, th.a Central and Ellesmera paid dividendls for several year'd on ore carrying! ;is low grade as 1 l-3dwts or worth 5s 4d per ton of 22401b-. Of course the ore \v:is easily "mined and crushed, but, noveithelfssi, the Water a,nd timber for treatment cost money. Thy Ntw C!lmm Railway and Victoria, Quartz Vere winding dirt from 4-360 feet. vertically, and, after payingl for mining timiber, firewood, and water, their win Jo costs only vnn into- silwt, or .£1 por ton. and anythino' abf)Vt -this was dividend money. At Ballarnt the Pli>uth Star paid tens of tlioup'ancla of ]xninds in dividends fvom ore that, did! not a^ieratfo n\ore than 3.4 dw'fcs per ton. and the depth wai-i 2100 feiet, and is now much lower. At the Homeward Bound, Yalivat. N.SVW., the ore did not avefajje 5s per ton, and, in addition to mining, required cirushins, concentration and cyanide for its efi'c-v-

tivo treatment. In Australia alone many such mines might te mentioned, 'but, as the we fields are many hundreds oi" miles apart, and all are working under most, ndverse conditions, compared! with Thames, they

will suffice. To refer to that much quoted mine, "The Alaska Trendwell/' the late* balance-sheet sshows the following figures: Value.of ore per ton, 2.26 dollars, or say 9s per ton ; total costs per ton, 1.37 dollar's per ton, OH' say 5s Bd, equal to roughly 3s id per ton treated!. After deduction of sundry charges for depreciation of plant," etc.,'the company paid a mvidend of 14 per cent per'annum. Of conrss. each, of the above cases must be taken on their merit si, but, m each ease, with the probable exception of the fetter, owing 1 to its great bulk the conditions arei more unfavourable than the Thames. (To be Continued.)