Mining development scheme for the Camborne-Redruth Northern Area

Mining development scheme for the Camborne-Redruth Northern Area


William Hoskins

April 27th, 1922.

As the result of lengthy discussions in the Cornish Institute of Engineers and the mature deliberations of the Council, the following recommendations are submitted with regard to the proposed mining operations in the Camborne and Redruth district.

The Plan of Mine Setts, showing their disposition and approximate relative boundary lines is marked No. 1.

The Plan of Mine Workings to be referred to later is marked No. 2.

Sections of Mine Workings are marked 3, 4 and 5 respectively.

(NOTE: The plans referred to are not included in the Transactions and therefore cannot be included here but most information can be inferred from what follows)

Reference will be made to these three schemes—A, B and C. The latter with its mineral resources and immediate prospects and the probable absence of difficulty so far as acquisition goes, is the scheme which will be put forward with every confidence.

To get the requisite information to present in legitimate form has taken some little time and trouble, particularly with a view to eliminating everything of a purely speculative character and tabulating as nearly as possible the plain facts in each instance.

It will be gathered in perusing these notes that scheme “A” from an economical point of view, would be the first to consider, but this, for reasons which will be explained later, has had to be put on one side pending possible negotiations between the parties who may be prepared to advance capital and those who represent vested interests at this end.

Scheme “A”. incorporates the following properties :—

1 Violet Seton. 2 New Seton. 3 South Seton. 4 West  Seton. 5 Wheal Seton. 6 North Roskear. 7 South Roskear. 8 Crane. 9 Emily Henrietta. 10 East Seton. 11 North Pool. 12 West Tolgus.
13 East Seton and Maud. 14 Wheal Robartes. 15 Great North Tolgus. 16 Tolgus United.
17 Old Tolgus.18 South Tolgus. 19 Great South Tolgus. 20 Wheal Tehidy. 21 Wheat Agar.
22 East Pool. 23 Tincroft (part). 24 South Crofty (which includes New Cook’s Kitchen and Wheal Crofty). 25 North Crofty. 26 Dolcoath (part). 27 Camborne Vean. 28 Stray Park. 29 West Stray Park. 30 Wheat Frances. 31 Wheal Nelson. 32 North Dolcoath.

Economically it is assumed the whole of these various interests should be fused and made into a huge Mining Corporation, in the hope of centralizing, as far as possible, all pumping and milling operations, and by appropriate shafts, either new or by re-construction, to attack the whole area
under one large scheme of constructive development, thus acquiring a maximum output with a minimum of overhead or standing charges.  In reviewing the situation, however, the factors represented by the live companies present such extreme difficulty that the possibility of fusion is to all intents and purposes beyond the writer, or the Cornish Institute of Engineers and can only be approached through discussion or conference with present companies by parties who would be willing to advance capital for the consolidation of those interests and financing them generally.

The Dolcoath Company holds a claim to much of the mineral ground to the West of Dolcoath proper under lease or license, and although the company is casting about at the present time in the hope of finding capital or securing Government aid to resuscitate its own propositions, it might
possibly present difficulties in the fusion of the whole. The same remark applies to South Crofty which incorporates New Cook’s Kitchen and Wheal Crofty, and holds under license the northern portion, known as North Crofty or Trevenson. This company is at present spending some
£30,000 to negotiate the water difficulty which rises by reason of the cessation of mining operations in East Pool and Agar. The consequent inundation of those two mines, and the
water accumulating in those joint properties is eventually finding its way into South Crofty, which company is putting up a new pumping installation incurring the expense before mentioned so as to keep their own mine dry and to prosecute a further development when better economic conditions for mining prevail. Consequently, whilst being willing to consider any proposition which might ultimately be advantageous to the South Crofty Co., in the absence of knowing the attitude
of the proposed investors, it is difficult to conclusively suggest to the South Crofty Co. how far a fusion of the total interests in this community would be of advantage to that company in particular, and pending any action of the proposed investors, they are carrying out their own scheme of operations which may be considered sound within their own area, but which
might possibly have covered a wider field of operations if the suggested fusion of interests was an accomplished fact.

The East Pool and Agar Company, to whose action the inundation of the old part of both East Pool and Agar Mines may be attributable, holds fairly extensive interests to the north and east of East Pool and Agar, and the independent attitude of that company, which cannot be too strong financially, although perhaps possessing the ability to acquire such monetary assistance as they may deem requisite, presents another difficulty in the consolidation of interests, and in a way perhaps more pronounced than the views expressed by South Crofty. They would be willing to consider proposals incorporating advantages to their company, but it is to be clearly understood that Dolcoath Ltd., South Crofty Ltd., and East Pool and Agar Ltd., would prefer, if possible, to maintain their separate undertakings, and as previously suggested, the proposal for a general consolidation, however desirable it may appear, does not come within the province of the writer
or the Institute of Engineers, and can only be approached with a probability of success by parties who are willing to consider the raising of capital for such a proposition.
These reasons will be sufficient for substituting a second scheme marked “B” and incorporating the whole of the mines body-coloured blue and yellow on the print. It will at once be apparent that the amount of capital required to inaugurate mining operations over the whole of this area,
approximately three miles long, will be almost, if not entirely, as much as would have been required for the fusion of the total interests of the whole of the mines in the district. It would have been possible, from the existing mines under Scheme ” A” to open out in North-Westerly and North-Easterly directions to intersect the various lodes standing in these directions and this would eliminate the preliminary necessity of shaft sinking. Scheme ”B” further incorporated the
possibility of getting out under the present bottoms of the old mines, with the probability of not being seriously handicapped by the water at present in such old mines, other than by percolation. This could be dealt with by the installation of either central, or subsidiary, pumping stations to prepare for the natural increase of water resulting from extensive mining operations for the wide area.

Scheme “B” involves the sinking of possibly three shafts, and having regard to the cost of sinking and the fact that although one may have the best reasons for inviting capitalists to prove the area comprised in this scheme, from an investor’s point of view, perhaps it has too much of the speculative characteristics, and having regard to its extreme length, might not be considered to be sufficiently certain of immediate mineral values to justify the putting up of a large sum of
money. In this connection it may be pointed out that East Pool and Agar and the Tolgus Companies, holding, as they do, large interests in the north and eastern mines would possibly present financial difficulties—not insurmountable perhaps—but sufficient to handicap a general scheme of such magnitude.

Scheme “C” has been evolved for that reason since it certainly does present factors of success, and one would place this scheme on record as offering the best possible inducement for mining operations, and one which is likely to yield returns as soon as the water has been negotiated, and further, the possible success of this scheme would always have the opportunity of being followed by important extensions eastward, so as to involve the greater part of the Scheme “B,” since this ground would be available.

In the area comprised in this scheme are the following mines :—All the Seton Mines, North and South Roskear, and possibly the northern part of Dolcoath.

It is a recorded fact that practically the whole of the mines in the Camborne – Redruth district were originally copper mines which in depth experienced a gradual transition and at a depth varying from 500 to 1,000 feet commenced and continued to yield quantities of tin.

Such a transition is accounted for on the grounds that copper is peculiar to lodes in the district so long as they remain in the “killas” or clay state, and tin is the metallic mineral in evidence near the line of contact between the killas and granite, where the lode passes from the former to the latter, and it may be cited that tin has been produced by the Dolcoath Mine down to a depth exceeding 3,000 feet in granite.

The granite out-crops are approximately in an east and west line, the intervening basins being filled with ” killas” which, superimposed on the granite, dips north.

It will be apparent that mines along, or approaching, the line of surface contact between the killas and granite, would quickly reach the granite in depth and thus account for the passing of the copper production and the occurrence of tin, and it was naturally assumed that parallel lodes, to the north of the Cam Brea Series, would in consequence of the northern dip of the granite have to go considerably deeper before one could reasonably expect such lodes to enter the granite and become tin producers. This assumption, coupled with the fact that the mines or cost book companies comprised in this area had disbursed their enormous profits, instead of conserving their resources and adapting their surface and mining plant generally for deeper mining and tin production, in the face of depleted copper reserves, ultimately led to the cessation of operations, although they were at that time producing tin.

It is now assumed that the production of tin from the bottom of the old copper mines was an indication of the comparatively near approach of the granite, and the late J. H. Collins held the opinion that, instead of the northern declivity of the granite being perpetuated indefinitely, the surface of the granite would probably be of an undulating character, thus being between actual outcrops much nearer the surface than formerly believed, and this suggestion “finds support in
the remarks made from time to time by eminent geologists. It may be noted in this connection that Mr. E. H. Davison, of the Camborne School of Mines, has found granite outcropping in a minor degree some two miles north of the series of lodes under observation.

Having regard to the occurrence of tin in the Roskear Mines and Seton Mines as the result of the gradual transition previously referred to, and the very striking analogy existing between these mines and the Dolcoath-East Pool Series; in the absence of any geological factor to obviate the possibility of tin production when the granite is reached, the Roskears and Setons should be equally successful.

The Roskears and Setons are practically unexplored in depth and yet have been large producers, as the following figures will show :—

Copper.               Tin.               Total.

South Roskear   £217,993        £15,160        £233,153
North Roskear   806,630         106,011          912,641
Wheal Seton      535,286          71,664          606,950
West Seton        719,341         454,836        1,174,177

TOTALS        £2,279,250     £647,671       £2,926,921

It is also interesting to note that subsequent to the cessation of operations in the above mines many thousands of tons of stuff have been taken from the burrows (waste heaps) and treated for tin, whereby various parties, including tin-streamers who could conveniently and cheaply provide power for carrying out the operation, had profitable undertakings, and it has come particularly within the writer’s knowledge that the West Seton burrows were treated over the years 1899-1902 and the following returns made :—

Tons   cwt.  qr.  Ibs.               £      s.   d.

Tin                     199      5      3   21            13,476   8   7
Copper              1,644   3      1   17             2,002 17 10
Arsenic              388      9      1    8              3,466  14   9
Burnt Leavings  823      5       0   0                  427 12   6
Tin Leavings      13       10      3    0                  23   8    6

Tons                   3,067   14      1  18              £19,397 2 2

The approximate tonnage crushed was 110,000 tons.

These figures will substantiate the suggestion previously made that, although tin was being sold by the West Seton Co., right up to the time of their closing down, the Company did not admit of their actually working for tin, and never made adequate preparations for effectively saving their tin output. In this connection details taken from promiscuous statements of account issued by the West Seton Co., towards the latter part of their working, show their tin sales as averaging approximately four tons a week, and in every probability these sales were effected under prevailing conditions which represented a very low extraction indeed.

The question of ore reserves in these mines is an important one. Whilst unable to procure tabulated statements relating to the same, references were made from time to time by the various companies as to the value of prospective points of development, such values being stated either in the number of Ibs. of tin per ton of ore, or their actual value sterling, per cubic fathom, and although there are grounds for anticipating many thousands of tons of tin-producing ground actually being laid open, it does not come within the province of the writer or the Institute to state what actual reserves, represented by a given tonnage of prescribed values, await the speculative
investor, but it is within the province of the writer to point out the probability of finding, even without development, large quantities of ore ground which with congenial economic conditions could be profitably mined, and so far as mining operations will admit of forecasting results, one would expect with further developments laterally and particularly in depth (having regard to the underlying granite) there is every probability of the tin lodes becoming permanent tin producers with continuously higher averages than could be looked for in the superincumbent killas.

Attention should be called to the geographical position of the mines and the relation they bear to each other and also the pumping operations which would be necessarily entailed in operating within the area and one may at once say that the South Roskear Mine stands alone since it is not connected with North Roskear or the Setons, which occupy two distinct lode channels to the north of South Roskear. The South Roskear main lode dips south and, in the event of the northern part of the Dolcoath Mine, which shows lodes dipping north being incorporated, this area would probably yield water having a maximum of about 200 g.p.m., or possibly a little over, since
South Roskear is quoted at being 160 fathoms deep at the deepest point and the water pumped being 156 g.p.m. as a maximum. A good central shaft could command the whole of this area and then the existing shafts could be made contributory for ventilation or other purposes.

The North Roskear Mine, standing to the north and parallel to the South Roskear series, has in the course of its eastern prosecution been associated with the North Crofty series of lodes and along the line of counter lodes more particularly has been linked up with Wheal Seton and West
West Seton Mines although the depth of these mines at their deepest may vary the control of the water is one which affects the three mines, suggesting that this area should be worked jointly.

To recapitulate, one shaft would be sufficient to work South Roskear and the portion of North Dolcoath, and another central shaft for the Setons, which ultimately could be linked up with the shaft set out for South Roskear and thus bringing into operation the North Roskear series of lodes.

The position of the shaft for working South Roskear and possibly the northern part of Dolcoath, could, if a vigorous scheme of development of the whole area were adopted, be approximated
sufficiently safely to command the North Roskear lodes. The existing shafts on the Setons and North Roskear would provide subsidiary shafts equal to all requirements.

North Roskear at the deepest point was 265 fathoms and water stated to to be 243 g.p.m. maximum.

Wheal Seton’s deepest deepest point was 250 fathoms and the water stated to be :

Tilley’s Engine 137
Tregonning’s    287
424 g.p.m. (1872).

West Seton’s deepest point approximately 300 fathom and water stated to be :

Harvey’s Engine 358
Rule’s                  252
610 g.p.m. (1890).

This would include part of the North Roskear and Wheal Seton water without doubt, since Wheal Seton and North Roskear ceased to operate.

It has not been considered necessary at this juncture to discuss the capital required, or the method of dealing with the water at present in the mines, since both these matters can more readily be considered when the general lines procedure are in progress.

In the following extracts from Reports, Statements from the Geology of the Falmouth and Truro, and the Mining District of Camborne by J. B. Hill, R.N., and D.A. MacAlister, A.R.S.M., F.G.S., 1906, are prefixed ” A”  from the late J. H. Collins  “ B.”, from Mine Reports “C”, from Records, Tehidy Office ” D. Miscellaneous ” E.”

“A.”—“The granite was never struck in depth in North or South Roskear. The copper ores appear to have been particularly abundant from the upper levels down to about 180 fathoms from the surface. Arsenical pyrites was abundant in South Roskear between the depths of 100 and 132 fathoms from surface. Tin ore occurred in the upper parts of the lodes at the western end of these setts (particularly North Roskear) associated with lead, zinc and copper ores. It first met any quantity at depths from 100 to 150 fathoms below surface and was of some value to the bottom of the mine. At North Roskear at the 205 fathom level West of Doctor’s Shaft, the lode is 21/2 feet wide and consists of quartz with copper pyrites and tin ore. At the 216 level, the lode was from 1 to 8 feet wide and contained quartz, fluor spar, chlorite, tin and copper. At the 203 level there was tin stone and mispickel but little or no copper. In the Eastern part of the mine on Engine Shaft at the 160 level the lode is 4 feet wide and contains copper and tin ore.”

” B.”—North Roskear.—”Was opened about the year 1800, profits secured at that working£90,000 ; reopened 1816 profits to 1843, £100,000.”

“from 1816 to 1856 151,797 tons of copper ore sold for £703,878
1857 to 1874 15,602  „      „      „                         £102,752
1855 to 1884  1,557  „      „      „                        £106,011”

“E.”—The Mining and Smelting Magazine, November,1862. The Editor reports (page 279) :-“This mine is now working for tin which is found as shown in the section under the old rich copper deposits. The tin was first found a little under the 84 level, but as the depth increased the lode is found to improve materially and there seems every prospect of this lode and the North lode making tin in depth. As already stated, the best lode is found about the junction which, with its Western lode and the North underlie of the lode which is rapidly dipping into Wheal Seton Sett.  Considering the size of the lode in the bottom levels and its highly promising character for tin, there can be no second opinion as to the excellent prospect it holds forth of making a tin ground of which it is now returning 10 or 12 tons a month.”

“B.” —South Roskear—” In 1867 the profits from South Roskear appear to be £300,000, the returns for :—
1821 to 1850 sold 37,807 tons of copper ore for £215,391
1851             „         258     „              „      „             £972

(Pendarves Consols).
1874 to 1881 sold 389 tons of black tin for £15,160
„    383    „   copper         „ £1630
NOTE.—These returns are incomplete, and it is said that copper ore produced up to 1843 was 500,000 tons.

” B.”—Wheal Seton.—”This mine commenced operations in approximately 1834.
1837 to 1847 sold 16,562 tons of copper ore for £80,000 (about)
1848 to 1876   „      96,481 „            „    „    „      £455,286
1856 to 1875   „      1,012  tons of black tin „    £71,664
” Greenstone at 135 fathom level—also greatly enriched both for copper and tin”

” E.”—” It is on record that one of the reasons for shutting this mine down about 1876 was the fact that the Company attempted in an arbitrary way to enforce an amalgamation with the adjoining mine, West Seton, but the adventurers of West Seton strongly opposed such a scheme and the representatives of the larger interests in Wheal Seton threatened to close down with a view of inundating West Seton. The latter company attempted by means of dams to prevent the passage of the water from Wheal Seton to their property, but it was found that percolation along the line of lode was so great that West Seton pumping charges became considerably increased by the addition of another pumping engine.” There are in existence to – day men who were associated with the Seton Mines and who will vouch for the accuracy of the above statement’

” B.”—West Seton.—” West Seton Mine began working somewhere about 1844 and gave dividends between 1855 and1878 of £239,850, on a called up capital of £19,000.
“From 1848 to 1890 the Company sold 125,768 tons copper ore, £719,341.
From 1875 to 1890 the Company sold 4,045 tons black tin, £217,959 (incomplete) and over 4,000 tons of crude arsenic.”

“D.”—The Tehidy Estates records just prior to closing down of the mine carry the following references :—
May 9th1889.— Mitchell’s Engine Shaft sinking below 275 fathom level; lode large and well defined yielding good stone of tin indicating a relationship with much better lode, worth £14 per cubic fathom or about £30 for length of shaft (13 feet).

275 E of shaft massive lode 30-32 Ibs. per ton for tin (£12 per fathom).

275 W of shaft good looking lode better part towards the North which yields good work for tin £12 15s. Od. per fathom.

264 W of the shaft poor, say worth £10 per fathom.

250 E of the shaft extended 50 fathoms, of which 30 were productive for tin (£12 per fathom).

238 E and W of shaft also referred to as worth about (£12 per fathom).

“October 18th 1889.—Mitchell’s Shaft still sinking, lode worth £25 per fathom for size of shaft (13 by 7) equal to £10 per cubic fathom.

275 E worth £10 per fathom averaging 1 to I1/2 for tin.

275 W worth £8 10s. Od. per fathom.

264 E  42 fathoms from shaft worth £15 per cubic fathom, stoping ground, width of lode 12-15 feet; £10-£12 per fathom.
264 W 32 fathoms from shaft 1 to 13/4% tin.

The average produce in two slopes in back of 130 level is 40 Ibs. per ton for tin (£16 to £18 per fathom).”

” February 17th,1891.—Mitchell’s Shaft being sunk below the 288 level; last six feet better appearance than for many fathoms ; hanging wall is killas, average yield for last six feet of sinking over a width of three feet is from 3 to 31/2% tin or from £15 to £18 per cubic fathom.

288 East is extended 15 fathoms from shaft.
288 West        „    18    „        „    „
275 East         „    36    „         „    „
275 West        „     50    „         „    „
264 East         „    50    „            „    „
264 West        „    60    „         „    „
250 East         „    52    „         „    „
250 West         „   112    „         „    „
238 East         „    56    „         „    „
238 West         „    128    „        „    „

In greatest part of these drives the lode continued large and, with the exception of the 259 east which yielded for a few fathoms a better produce stuff, it was uniform in character, composed of quartz width a little chlorite and in places finer spar and a small percentage of tin averaging not more than 1 to 1/4 % throughout. Since the lode ceased to yield copper to any extent, that is below the 130, there has been underneath two distinct shoots of tin, one about Mitchell’s Shaft, the other west of it; those contiguous are not very far distant from the elvan (and with which the yield of copper was associated) yielded quantities of tin stuff of a good average, but as depth was attained and the distance from the elvan increased, the lode lessened in produce and value and the mine less hopeful as a speculation.”

In addition to the above, Mr. W. H. Blight, who was the assistant purser at Seton, estimated the tin values in West Seton at from 28 to 32 Ibs. of tin per ton in the lode (this would obviously refer to the deeper levels). It has also been stated that the total profits divided by West Seton were over £250,000 from its workings to the north of North Roskear. Captain Mitchell, who is available to-day, has certified that in the 264 east of Mitchell’s Shaft and about 15 fathoms from shaft that lie (Mitchell) and his men suspected the presence of tin lodes running parallel to the lode already stoped, and on drilling into the northern part and blasting, they opened a rich tin lode, five feet wide, worth from 5°/o to nearly 8% of tin. A number of men tributing in the level above, hearing of the discovery, found the same conditions existing there, and also on the same level west of the shaft. It was thus opened out at three points much to the disgust of the agents, who had
missed it. The said discovery took place about six months before the mine closed. Mr. Mitchell corroborates a statement from Mr. Blight as to the high arsenical value of the ores and further states they did not consider 28 Ibs. of tin to the ton worth troubling about.

New Seton, Violet Seton, South Seton.—These are mines standing west, the returns having been almost negligible by reason of the shallow depths attained. They may be considered almost virgin properties and could be incorporated under any scheme of development.

The next reported reported meeting of the Institute was not until 24th February 1923 when the President reported that the comprehensive scheme which had been discussed by the CIE had been divided in two for the convenience of the Dolcoath Group and the district generally and he hoped Dolcoath would succeed in the flotation of half of it. He understood that matters were moving in the right direction and that further intercession with the Trades Facilities Committee of the Government was likely to help the scheme. In the Camborne – Redruth area there were indications of industrial improvement.

On 8th March 1924, the President said that much work had been put into the big scheme of development of the Camborne – Redruth mineral area. Some said the scheme was too big to be carried out under the depressed circumstances through which they had recently passed. However, if one looked at the area today the there would be evidence of the Institute’s own plans from east to west, from Tolgus to Roskear. Moreover, the continuation from the Tolgus eastern boundary to Peevor was under grant to companies or to responsible individuals.

There was no further reference to this scheme in the Transactions and it is not clear what, if any, influence it had on the industry. However it is true that with some Government aid there was some increased activity at New Dolcoath which included the sinking of a new shaft at South Roskear although in the end this had little effect and Dolcoath ceased operation in 1929 with large debts owing to the Government which appointed a receiver to wind the Company up in 1930.