Section IV., 1885. [ 23 ] Tran.s. Koy. Soc. Canada. 
 
 II. — On the WdVbr'ahje Hematite Mine, m ilhistratin<j the StocL-fonned Mude of 
 Occurrence of certain Orc-Deposit)i. By E. .T. Chapman, Ph. D., LL.D. 
 
 (Koiul May 2S, ISSo.) 
 
 Metallilerous deposits, viewed broadly, may be regarded as falling- under the follow- 
 ing sub-divisions : Veins, stocks, net-works, gash-lodes, impregnations, beds, alluvions. 
 Briefly defined, without regard to accidental or local conditions, these are characterized as 
 follows : — 
 
 Veins are ancient fissures filled up, Ibrming, as a rule, comparatively narrow sheets of 
 mineral matter, which commonly pass through various kinds of rock withoiit regard to 
 the strike or dip of these, and which, normally, extend downward to great depths. 
 
 Stocks arc limited masses of ore, although often of large dimensions, lenticular or 
 irregular in form, and inclined or horizontal in position. In some cases, they <'onform 
 more or less to the structural characters of the rocks in which they occur; in other and 
 perhaps the majority of cases, they shew no relations of this kind, but occupy a totally 
 independent position as regards the enclosing rock. 
 
 Net-wouks, sometimes called Stock-works, are assemblages of narrow, reticulating 
 veins, branching irregularly through the enclosing rock, and commonly tapering ofi" and 
 dying out in thin striims. 
 
 (lASii-liODEs are simply narrow, often more or less linear, stocks, usually of short 
 length, but commonly occurring in closely adjacent parallel bands, thus resembling a 
 series of short, broken veins. As a rule, they consist wholly of metallic matter, without 
 any accompanying veinstone or trace of vein structure. 
 
 Impkeonations consist of metallic matters diftused through zones or areas of rock in 
 small, often imperceptible, particles, or in patches or stains. Impregnations or difl'usions 
 of this kind are occasionally of independent occurrence ; but more commonly they occur in 
 intimate connection with veins, stocks, or other ore-deposits, being evidently emanations 
 from these, or otherwise due to similar causes. 
 
 Beds are deposits of mineral matter lyinii' parallel, or practically parallel, with the 
 stratification or foliation of the rocks in which they occur, and never extending upward 
 in strings or other prolongations into the overlying rock, as they are necessarily of earlier 
 deposition than the latter. 
 
 Alluvions cannot strictly be separated from beds proper, as they are simply beds or 
 bedded deposits of more or less superficial occurrence, but for practical ])urposes they are 
 conveniently classed apart. They consist of accumulations, from springs, streams and 
 rivers, of detrital or precipitated matters in which metallic substances or other economic 
 products are present. 
 
 As regards Canadian iron ores, the existence of stock-formed deposits hardly seems to 
 have been recognized, if recognized at all, in the earlier explorations of the ctmntry. Many 
 of our iron-ore dei>osits, perhaps the majority, are nevertheless in that condition. In the 
 
24 K. .1. CirAPMAN ON THE 
 
 examination of a deposit of irou ore, as revealed by natural exposures, or laid ])are by 
 trenches or trial-pits, the presence of a stoik-lbrraed mass may be inferred in most cases 
 from the great width of the deposit, and especially — whether of abnormal width, or other- 
 wise — by the variations in width, and consequent irregularity of outline, which it 
 exhibits. In the case of magnetic ores, these indications are often si.iUciently revealed 
 by the dipping-needle. 
 
 A very instructive and unmistakable example of a stock-formed ore-deposit is furnished 
 by' the "U'allbridge Hematite Mine, on the twelfth lot of the fifth range or concession of 
 Madoc, one of the southern townships of the County of Hastings, in Ontario. This mine, 
 now practically exhausted, was opened about sixteen years ago by the late Thomas 
 Campbell "Wallbridiic of Belleville. Since that date, with 0(?casional stoppaues, it has 
 been extensively worked, and has yielded many thousand tons of red iron ore of very 
 superior quality. 
 
 The geological features of the district in which the mine occurs were indicated 
 briefly by Mr. Thomas Macfarlane in his Report on the County of Hastings, published by 
 the (rcological Survey in iSiH!, and more elaborately by the late Mr. Vennor in his ab^c 
 Report of 1869 ; but as the mine had not been opened at tht>se dates, no information tould 
 at that time be given as regards the nature and extent of the deposit. It was previously 
 known that the rock formations of the district are essentially of Laurentiau age, overlaid, 
 here and there, unconformably, by outlying patches of Ijower Silurian limestone, now 
 called '• Cambro-Sihirian '" by the present Survey. According to Mr. Vennor, the Lauren- 
 tiau rocks of this section of country form a series of roughly-parallel synclinals with gene- 
 ral N E and S W strike, and consist of a threelbld subdivision, comprising (in ascending 
 order) : (1) syenitic and gneissoid rocks, essentially red in colour, with some crystalline, 
 graphitic limestones ; (2) dark-green, amphibolic and pyroxenic rocks with associated 
 irou ores ; and (3) various micaceous and siliceous slates, crystalline limestones, and con- 
 glomerates, mostly of a greyi.sh colour. Whilst the general accuracy of this distribution 
 is undeniable, I think it would be preferable to reuard the series as consisting of four, 
 in place of three, groups, — two of these being probably eruptive or intrusive, while the 
 other two are undoubtedly metamorphic strata i_i the ordinary sense of the term. T would 
 thus separate, from the lower stratified iineisses, the uustratified syenites or syenitic 
 granites, the elevation of which has caused the synclinals determined by Mr. Vennor. 
 The green, amphibolic or pyroxenic rocks are of dou])ti'ul origin. Although in places 
 they graduate into schistose layers apparently cf)nformable with the underlying gneisses, 
 in other places they shew no distinct stratification, and at certain spots, as pointed out by 
 Mr. ]\[acfarlare, they present even a sub-columnar structiire. I believe them to be for the 
 greater part, if not wholly, eruptive overflows or intrirsive beds from which the iron 
 deposits have separated during consolidation. In many places they are scarcely repre- 
 sented at all in the series, or merely form the sheaths or enclosing rock of the irou ore. 
 They differ, thus, in a very marked manner from the extended gneissoid l)eds which lie 
 beneath them, and from the slates, crystalline limestones, etc., by which they are imme- 
 diately siacceeded. Here and there throughout the district, these crystalline rocks are 
 overlaid unconformably by outlying patches of lossiliferous and nearly horizontal lime- 
 stones of the Lower Trenton horizon. The elevation of the red syenites, therefore, if Post- 
 Laureutiau, muut necessarily have preceded the Cambro-Silurian period. 
 
^^•A MvHKi I »( ; k ii kmatite m i n k. 
 
 23 
 
 The position ol" tho hematite deposit, ioriniii<j; the Walll)iicl<re Mine, is at the snnimit 
 ol' the lower gneissic series, or inunediately at the base of the upper series. Tlie mine, 
 itself, occurs on the twelfth lot of the fifth toncession of Madoc, about four miles north of 
 Madoc village. The ore, now exhausted, was in the form of a large " stock '" or irregular 
 mass, partly encased in and mixed with green amphibolic rock; but the latter is very 
 sparingly present at this locality, and, as shewn by shafts immediately adjacent to tL'^ 
 mine, it does not extend many yards beyond the site of the ore. The hematite has been 
 mined by open (jnarrying, and the large excavation which has thiis resulted shows the 
 original mass of ore to have averaged about 170 feet in length, by about 10(1 feet in breadth, 
 with an average depth of eighty feet. The weight of this mass would exceed 200,000 
 Canadian tons. Here and there, as in stock- formed masses generally, the ore has thrown 
 out wedge-shaped prolongations into the surrounding rock ; but th^-se, when followed up, 
 have been found, in every instance, to terminate more or less abruptly at distances of a 
 few feet or yards. The floor of the excavation is now on bare rock, but in order to test the 
 pit thoroughly, the h ssees have sunk upon it a couple of small shafts, seventy-live feet 
 apart, and about thirty feet deep, and these have been con net ted at the bottom by a narrow 
 drift. The latter passed through barren ground, all the way. 
 
 
 / 
 
 i^ 
 
 B 
 
 fStV. 7^ 
 
 
 
 'c^--^ 
 
 12; V. 
 
 Q) 
 
 \Z',y\. 
 
 
 5D 
 
 D2 
 
 1 
 
 \ 
 
 
 3 
 
 ■n 
 
 
 
 
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 KXl'l.ANATI'iX : 
 
 A, A, CovxTY UOAJ). B, SiDK i!(>.\i). I.Lahoe excavation i.kf:' by hkmoval of okk at Tin; 
 
 WALLiiRiiKiB Mink, on lot twei.vk, conci^siox five, Maixx'. L'. Engine hoise. 
 
 3. Shoot. 4. Tkamway. 5, .i. Sheds. 0. SiiAFr of >Iili.er Mine 
 
 on lot twelve, coscessios six. 7. Shai-t on 
 
 lot tiiiiitekn, concession five, 
 
 It was at cue time thought that the deposit extent oss the (ountry road, in an 
 
 easterly direction, into the twelfth lot of the sixth coi . on ; bat although there are 
 
 undoubtedly, indications of a slight extension in this dirt .on, siibsequent explorations 
 
 See. IV., ISSo. 4. 
 
26 K. .). OllAl'MAN (>\ TIIK WALMJin iMiK JIKMATITK MINK. 
 
 have shown that, Imtli here and iu the main pit, the ore is practieally exhausted. No. <!, in 
 the annexed sketch-phm, indicates the position of a shall sunk on this supposed extension 
 to a depth of nearly seventy feet. Drifts were rnn in an easterly and westerly direction, 
 to a distance of abo\it twenty feet from the bottom of the shaft. These workings were 
 known as (he Miller Mine ; bnt in one drift little more than poor, fragmentary ore and 
 iron-stained rock was met with, and in the other the indications were not suthcient to 
 warrant further ontlay. No. 7 shews the position of another shaft, sunk (against ndvice) 
 to about the same depth of seventy feet, immediately north of the AVallbridge pit, on the 
 thirteenth lot of the lifth concession. This passed through some light-grey crystalline 
 limestone and then entered the underlying gnessic strata, meeting only with a small 
 string of hematite, and with little more than traces of amphibolic rock. 
 
 A sample of ore taken some time ago from the l)ody of the Wallbridge pit, contained 
 by my analysis 97.18 per cent, ferric oxide, equivalent to (58 per cent, metal, with only 
 2.78 per cent, amphibolit^ rock-matter : whilst the best sample that I could get from the 
 bottom of the !Millcr shaft ' contained 23.43 per cent, rock-matter with much free silica 
 in it. and a second sample held no less than 2!>.32 per cent, rock-matter. 
 
 As the working of all stock-formed deposits must necessarily be followed sooner or 
 later by the exhaustion of the ore, and as no surface indications will enable one to predict 
 with any certainty the amount of ore present in a stock-formed mass, areater caution than 
 usual is re(|uired in handling these deposits. Happily, in the diamond drill, we have the 
 means of testing rapidly and economically the dimensions and general purity of ore-masses 
 of this charactt'r. By a few borings put down at short distances beyond the visible or 
 supposed limits of the deposit, and in the central part of the deposit itself, not only can its 
 dimensions be safely ascertained, but the cores of ore brought up by the drill will afford a 
 thorough insight into the character of the deposit, from depth to depth, throughout its 
 entire mass. 
 
 ' .\t tlio (Inte of my vLsit to tliis so-callod mine, tlio drifts won> entirely clused, so tliat T could not <rot into 
 them.