EAST CORNWALL MINES AND POWER CO.
GENERAL RESUME AND OUTLINE OF PROPOSITION.
The Bodithiel, The Goonzion and Penhale Mines
In East Cornwall, and Joint Power Installation.
Situation and Access.
These properties lie in the
parishes of St. Pinook, St. Neot and St. Cleer, respectively. The main line of
the Great Western Railway from Penzance to London passes over the Northern end
of the Bodithiel Mine about 1½ miles West from Doublebois Station and 5 miles by
county road West from Liskeard, which is 17½ miles West from Plymouth.
The Goonzion Mines lie some 2 miles in a direct line North from Bodithiel,
and about 3¼ miles North-west from Doublebois.
The Penhale Mine lies 3¾
miles
or thereabouts, almost due East from the Goonzion Mines, and between 4 and 5
miles North-East from the Bodithiel Mine. It is approximately 3 miles North-East
from Doublebois, and 3½miles
North from Liskeard Station.
The seaports of Plymouth, Fowey and Looe are situate 17½,
about 12 and 7 miles from Liskeard, respectively.
Reference to the Sketch Map attached will serve to clarify the foregoing.
It will be seen there from that the three properties form the points of a rough
triangle.
Topography and Water-Power.
Deriving its large and always permanent volume of water from the
Bodmin Moors, 1,000 or more feet above sea level, the Fowey - or Drains -
River, flows first South-Westwards within about 1 mile of The Penhale Mine and
after falling in a long series of cascades some 500 feet in about 4 miles, flows
Westward towards tide-water at Lostwithiel, above Fowey. In doing so, it forms
the Northern boundary – at Midstream – or The Bodithiel Mine, which has the
right to deflect half its current for power purposes.
Joining the Fowey about 1mile East or upstream from Bodithiel, is the
mouth or confluence of the St. Neot river – forming the North-Eastern boundary
of the Goonzion Mines, 2½miles
Northwards.
A further reference to the Sketch Plan will now make the position of the
three properties in regard to each other and to the railway and rivers named, a
deal clearer.
Minimum or Dry Season Power Available.
At a point 1 mile West from Penhale – and from one installation only – at least 1,200 hp. may be cheaply generated. This power can be multiplied many times over by the installing of one Turbine Station below another on the aforesaid course of 4 miles covering the fall of some 500 feet.
At Goonzion and Bodithiel, about 800 h.p. should be jointly available – as to 200 or 300 hp. at the first, and the remainder at the last named property
Assuming the installation of separate plants at or near each mine – such plants, of course, being “linked up” – 2,000 hp., or thereabouts, should be on call, at the driest season of the year.
As for several years not more than one-half of this power would be required for the 3 mines, bout 1,000 hp. would be disposable. Gas, in Liskeard, costs 7/6 per thousand, so that an eager, near-by, and very profitable market is assured.
It is conservatively estimated that the Capital Outlay upon Generating and Transmission Plant and Installation thereof should not exceed from £14,000 to £15,000 all told. The rent derivable from the said sale of the surplus 1,000 hp. would in itself pay a good dividend upon this expenditure, which would also be a local boon.
From the standpoint of the
mines, the saving assured in working costs would be enormous.
In the deep Tin Mines of West Cornwall for the last few years the power costs
for pumping and hoisting (coal, labour, machinery and up-keep) have been nearly
40 per cent., or eight shillings in the pound. Including such surface power as
that consumed for milling the ores end in various ways, it may be safely said
that about 60 per cent., or say twelve shillings in the pound of the costs at
these mines have been in power only.
Adit –Mining Facilities.
All three mines herein dealt with will be worked by Adit for many years.
The Bodithiel Mine has average “backs” (ground between Adit and Surface) of some 370 feet upon 3 lodes, for just on 1 mile.
For years, therefore, there will be no need to sink and equip shafts upon these properties – or with the one exception of a shallow shaft on Penhale Mine. Ore, debris and water will all be dealt with by Adit-drivage as shown.
The very considerable expenditure upon actual shaft-sinking, and the much greater and very heavy outlay upon pumping and hoisting machinery, amortisation and up-keep costs of same, need cut no figure for a long term of years.
Cheap, but good labour.
West-country labour has always been cheap – the present wage for skilled miners being from 40 or 42 to 50 shillings a week, only.
There is no Trades Union in East Cornwall, nor is there likely to be one for many years. The miners are not only skilled and loyal men, but they are of a type holding small farms – or “crofts” – in the district, independent and industrious. Ample numbers of such men are available, many of them returned in middle age from foreign mining camps.
Timber.
Larch (and oak) timber grows in abundance in these moorland valleys, and is sawn locally near Doublebois Station. Such timber – up to 10 and 12 inches diameter – can be bought, sawn to length as desired, for about 9d. Per running foot: just one-quarter of what it costs after defraying railway charges upon it at the deep mines of West Cornwall.
The foregoing favourable factors of situation and access by rail and sea; of practically unlimited Water Power too be cheaply generated; of Adit-mining facilities for many years; of low priced but very efficient labour, cheap timber, etc., form a unique combination from the economic standpoint.
MINING
Geology.
The relation of the sedimentary to the eruptive rocks, the Lode Systems of the district, etc., etc., will be more readily grasped after reference to the One-inch Coloured maps of the Geological Survey herewith; Nos. , , , and .
For a varying distance of 10 to 12 miles or thereabouts from the sea-coast inland – Northwards – the prevailing “country” is of lower, Middle and Upper Devonian Clay-Slates and Shales; intruded by both Acid and Basic dykes, as shown by the Survey Sheets.
The Mineral riches in these Sedimentary areas are in the North and South Silver-Lead, and (occasionally true Silver lodes; carrying, at times Argentiferous-Copper and small values in Nickel and traces of Gold.
The Silver-Lead ores – from this Smelter’s standpoint - are very “clean” carrying practically no Zinc, Arsenic or Antimony. The Silver values in these Argentiferous-Lead and Grey Coper ores show the highest averages for such products ever mined in Great Britain – varying from 40 or 50 to, in some cases, 150 or more ounces per ton of “dressed” Lead ore or Concentrate, assaying 70% Lead metal.
The true Silver ores – the lodes carrying them - were worked off and on in this and other Cornish and Devon areas from the Norman Conquest and earlier; a total production of some few score million ounces being recorded. Since the first few decades of the Nineteenth Century, however, Silver-mining, per se, has bulked very small in comparison with the enormous production of Tin, Copper and Silver-Lead ores in these counties. Nevertheless, it is within the writer’s certain knowledge (himself an old Silver miner) that in the Liskeard district now under review there are not only a large number of unexploited or partly-developed high-grade and highly profitable Silver-Lead lodes, but also other lodes which are properly Silver-bearing.
In this connection, it should be stated that these lodes cannot, of course, be compared in size with the huge Silver lodes and Argentiferous ore-bodies of the Western United States or South America or Canada; but they are, some of them, quite “sizeable” and persistent deposits – and the ores broken from them are exceptionally rich. J.H.Collins says that these West-country Silver ores have averaged about 400 ounces per ton of crude ore as mined; a higher average, probably, than from almost any like area the world over.
As an example of how rich these rich ores may be, I attach detailed statement of the sales of 304 tons of true silver ores from Ludcott Mine near Liskeard, realising £22,500 – or £73 odd per ton for the precious metal in the crude ore as broken; the Lead values were negligible. Some of this stuff was nearly pure Native Silver - sold at the rate of £4.500 to just over £6,000 per ton; but there were many “parcels” of a few tons apiece sold at prices of from £500 to £800 per ton, as will be noted.
These sales are typical of various others from the district though – for the last eighty years – such silver ores have been mostly discovered “adventitiously” in mining for Cooper or for Argentiferous-Lead. The writer repeats, however, that these ores do still exist – which fact he is demonstrating at The Bodithiel mine.
Reverting now to the structural geology of the district: at about 10 to 12 miles inland, the sedimentary strata are intruded by the main granite “back-bone” of Devon and Cornwall – running from Dartmoor to the Land’s End – from which the slates and shales have been denuded away both to the North and South of this Easterly and Western vertebra.
It is just along or inside of these two lines of contact (be it in the slates or in the granite) to the South and North of the granite intrusion that the large majority of the East and West, or (as Collins terms them) the “right-running” lodes – Tin, Tungston and Copper-bearing – have their origin; and have proved to be about the richest, the most deep-seated and permanently mineralised fissure-lodes that have been mined anywhere throughout the world.
These “right-running” lodes carrying Tin and Copper, it must be always remembered, are close to the contact between the slates and the granite, as just now observed: at a distance of a few miles from the contact lines – out into the “cold” slates or “cold granite, s the case may be, the fissures become much fewer, less persistent in depth, and very much less mineralised.
The merest glance at the lode-systems shown on the accompanying Survey Sheets at once illustrate this.
With this preface – it will be seen why the three properties herein dealt with have such peculiar elements of success predicted, from the Geologic and Mining standpoint. They are – as to Bodithiel and Goonzion – at no great distance from the contact in the first instance, and actually adjoining the contact of the slates and granite in the second instance. At Penhale, this line of contact passes through the bisects the property; one of the principal lodes - - the Southernmost – generally filling the contact-fissure.
The District’s Production.
Few detailed records are available in published form before well into the Nineteenth Century; although alluvial and to some extent, lode-mining also have been continuously prosecuted since Pre-Roman times.
Dealing first with lode-mining for Silver-Lead and Silver ores – at times accompanied by Grey Copper, Nickel and Gold in small quantities – this industry, in number of mines opened up has been far less fashionable and less prosecuted than has been Tin and Copper mining. That this is the case has but little to do with the potential merits of Silver-Lead and like mining here, and Collins, p. says:-
“There are, indeed, hundreds of square miles of similar
“ground in East and North Cornwall where traces of Lead
“may be found in the cross-courses, any one of which
“might prove to be, if followed up, as rich and important
“as the mines above mentioned .”
Speaking, however, of the half-a-score or so of Silver-Lead mines of the Liskeard district worked during the Nineteenth Century – nearly all of them dividend-payers – the recorded figures show a production of 91,270 tons of Lead ore or Concentrate containing 63,572 tons of Lead metal, and 2,925,385 ounces of fine Silver.
These figures, however, are incomplete even as regards the Lead, and as regards the Silver – do not account, probably, for much more than one-half of the precious metal. This is so because, for many years, the miners (vide the old records) were unaware that their Lead ores were rich in Silver – and the smelters, of course, did not enlighten them. Evidence of this can be adduced from the sale figures of all these mines: at Wheal Mary Ann, for instance, the production of nearly 70 per cent. Lead concentrate totalled 29,600 tons from the year 1848 onwards; the yield of Silver is only recorded as from the year 1854, but still amounts to 1,126,130 fine ounces.
An actual production from these eight or ten mines of very close upon 100,000 tons of Lead metal and, at least 5,500,000 ounces of fine Silver can be safely assumed, during the period 1848 to 1880 alone. At to-day’s low prices, these figures represent £2,500,000 for Lead less smelters’ charges, and about £825,000 for the Silver marketed. +
Very large though on complete values and tonnages for Tin and Copper have been recorded for this district, from the year 1835 onwards.
Going back through the centuries and taking into account the enormous production (of Tin) then mostly alluvial, the figures are staggering; but from the third decade of the
+Note. The official record of 2,925,385 ounces of Silver from 91,270 tons of Lead concentrate, shows an average content of about 32 ozs. Ag. Per ton; whereas 5,500,000 ozs. From say 100,000 tons shows an average of 55 ozs. Per ton. The difference is not only die to the unrecorded Silver from the Lead sold, but to the unrecorded sales from the true Silver ores – such as the £22,500 worth from Ludcott Mine, already mentioned on p. 5, which have not been recorded in the official statistics.
Nineteenth Century to the year 1911 alone, the production of Tin Oxide from Lode-mining (about 70 per cent. metal) is given at 22,1171/2 tons; and that of Copper at 896,322 tons of crude ore containing 66,038 tons of metal: equivalent, that is to say, to about 7½ per cent. ore, as mined.
At the varying prices for Copper over this period the above production is said to have realised just on £6,000,000; and taking Tin metal at its present low price of say £150, the aforesaid tonnage works out at £2,322,337, less smelters’ charges on the Tin sold.
From the few dozen mines of this small district, therefore-and from no further back than the year 1835 when Copper mining began – we have minimum sales of :-
Tin Oxide, or Black Tin Concentrate ... £ 2,322,337
Silver-Lead and Silver Ores ... £ 3,325,000
Copper Ores, say ... £ 5,750,000
--------------
Gross Total ... £11,397,337
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Dividends of at least one-third of this sum were distributed locally.
Huge tonnages of Tin Oxide, as stated, were won centuries ago from the surface alluvials, and mute evidence of this is still glaringly obvious in the gigantic “pittings” and “furrowings” of these areas.
That the Tin production during the past century for which the figures are given has not been much larger from lode-mining is due to the facts that the upper portions of most of these lodes (like the famous lodes of West Cornwall) were first Copper-bearing, and that the depth of some at which this mineral became poor coincided with a prolonged period of depression in the price of Tin, which still remained at depths of anything from 700 to 1200 feet, where the Copper gave out.
With patience, judgment and sufficient capitol, there should be no question but that immense bodies of highly payable Tin ores could be exploited below some of these old Copper Mines; but very large cash outlays might be involved, and while there are still virgin – and almost virgin – properties such as Goonzion and Penhale, where (owing to denudation) the Tin values are close t, or right at, the surface, and have been proved to exist there, the reopening of old and waterlogged mines has no particular attraction.
BODITHIEL, GOONZION AND PENHALE MINES
All general data concerning these three properties being already given, and itemised and detailed reports upon each mine accompanying this statement, all now needed is to briefly summarise the particulars in each case and deal shortly with the policy necessary to complete development; the approximate outlay involved; and the profits anticipated.
THE BODITHIEL-SILVER-LEAD MINE
This property, of about 267 acres, is in the shape of an oblong plateau, sloping abruptly to the North, east and West, and rising Southwards.
It covers 3 lodes for just one mile along their strike ?????? feet above Adit. It is nearly half a mile wide.
It is bounded by streams both to the East and West, and by the Fowey River at the Northern end: Water-power to the extent of 500 hp. or more is always available.
Two of the 3 lodes are Silver-Lead bearing, the “Eastern” or “Centre” being the northern extension of the very rich Herodsfoot lode worked 3 miles South, at great profit. At Bodithiel, a Deep Adit upon this lode was driven nearly 800 feet South about 50 years since by working miners. The lode was 3 to 5 feet wide and almost continuously productive: the high-grade, hand-picked ore ( and the lower grade after jigging) assayed over 70% Lead Metal and carried 130 ozs. And more per ton of Silver. With the demonetization and big fall in the price of Silver (1871) and the coincident fall of nearly fifty per cent. in the price of Lead with the first shipments home from Australia - and having no resources but the ore they were selling – work came to an end.
For Engineering reasons – vide Plan and Sections – work was begun 3½ years ago upon the Western lode; exploited, in a small way, 120 years since for the rich Silver ores – carrying a little Grey Copper and Nickel – which are again being developed. After about one year expended in re-opening the old workings – badly “caved” – the two following years, working on one shift only, were occupied in driving South some 500 feet in virgin lode of highly-profitable milling grade. This ore – of which 3,000 or more tons are already available above adit – averages about 20 ozs. fine Silver, 2 to 3% Lead, and some Copper and Nickel. By Minerals Separation Flotation tests, it concentrates in the ratio of about Eleven to One, showing recoveries of 94,30% Silver, 96,00% Lead, and 92,60% of the Copper present. Allowing, however, for only a 90% all-round extraction, and deducting a wide margin of costs, there is a nett-minimum profit of 28 shilling per ton :- calculated upon a milling basis of 15,000 tons of 20 ounce ore per annum from this lode only, and taking fine Silver at half-a-crown an ounce – it is now over 3/- - and Lead and Copper at £20 and £60 to £70 per ton, respectively. Upon this basis each penny difference per ounce of Silver adds £1,125 to the foregoing profit of £21,000 yearly. With fine Silver, therefore, more than 6d. per ounce higher as it now is, this additional profit amounts to £6,750 or to £27,750.
As stated, these figures apply to the Silver-Copper ores or milling-grade from the Western lode only; the returns anticipated from the exploitation of Silver-Lead ores on one or both of the parallel lodes about 400 feet and 900 feet Eastwards might easily double, and more than double, these figures from milling-grade ores.
From December of last year to date, Silver and Copper ores of a very much higher grade have been discovered on this Western lode in some quantity. For well over 100 feet driven – in addition to the milling ore – there has been a continuous “stringer” of from a few inches to about a foot thick (at one point an ore-body of over 5 feet thick and at the date of writing over 2 feet) assaying from 100 to about 190 ounces per ton in Silver, with 5 to 11½per cent. Copper, 3 to 5 per cent. Lead, and small Nickel values. The ore is a quartz-breccia with all the mineral in the secondary or cementing silica – the most positive evidence of persistence at depth. The Silver, Copper, Nickel and Lead ores are present entirely in sulphide form; as Argentite and Frieslebenite carrying the bulk of the Silver; as Chalcopyrite and Argentiferous Grey Copper ores; as Kupfernickle, and as Galena. Practically speaking, no Zinc, Arsenic or Antimony is present.
One does not desire to dwell too much on the possibilities of these high-grade ores, but that they will be found to persist – and in considerable amount – both in strike and depth, the writer is satisfied.
As a 100-oz. ore – carrying about 5 per cent. Copper – is now worth over £18 as mined, and leaves a nett profit at the South Wales Smelter of nearly £10 per ton; and as this ore can be concentrated at least five to one, thus saving more than £8 per ton on smelters ‘ charges on four-fifths of the tonnage – some little idea of profit from these rich ores may be arrived at.
To complete the Development Scheme upon this property – more than half accomplished – so that within 12 months from date it will not only be needful to put up a Flotation Plant to deal with 15,000 tons of yearly milling ores from the Western lode, but to consider also a Jigging or other Plant for a perhaps larger tonnage of Silver-Lead ores from the Eastern or Centre Lode – a sum of £5,000 is now required. This will provide for a Compressor and will defray all running and other charges in completing development. Thereafter, from £5,000 to £8,000 for Treatment Plant will be required (as to whether the ores from the Western or from both lodes are forthwith provided for) and the property will at once be profit-earning.
In addition, however, to the £5,000 to complete development, plus the further sum of £8,000 on Treatment Plant to be expended this year and next as developments indicate, there should be a substantial balance provided for – at some later date – shaft sinking and other purposes.
In view of all these contingencies a total available Working Capital of £25,000 should be provided for, although less may be needed.
The Lease held is for 42 years; the annual rent is £50, merging into a Royalty of 45 upon all minerals sold.
THE GOOZION MINE.
Here also we have a property which may well be described as a “plateau” – of about three-quarters by half a mile in extent, covering 240 acres. It slopes abruptly to the South-East and East, and even precipitously to the North-East and North – to the St. Neot river.
The Sett is traversed by eleven or more lodes (2 Copper and 9 Tin-bearing) in a generally speaking Eat and West direction. The surface plain is scarred and “furrowed” along the backs of these lodes – or most of them – by diggings (sometimes) of several hundred feet in length, 10 to 30 feet wide and of all depths down to 30 feet or more. These workings for the greater part are of remote age.
At the foot of the North-Eastern slope – it might almost be styled “cliff” – is the mouth of the deep Cross-Cut Adit, still open, in firm ground and in good r4paair. Some 60 years since (when Copper mining was at its zenith but the price of Tin was low) a small local company (with about £900 cash available) drove this Adit nearly one-fifth of a mile Southwards. They intersected 3 of the 11 lodes, the first of which was 3 feet wide and rich in Tin, showing recovery-values of about 3% Tin Oxide under Cornish Stamps. The two other lodes were larger but were low in Tin where intersected, and contained no Copper of much value. Having sold 18 tons of Black Tin and 9 tons of Copper, and not having the means to continue searching for more of the latter, and the price of Tin being very low, they stopped. The then Mine Captain, however – now dead –one of the best miners who ever lived, expressed his firmest belief in this property to the writer - in which belief the writer concurs. The geologic conditions are ideal; the lodes are numerous and strong and must have been extensively mineralised from the obvious evidence of the surface diggings of the most extraordinary extent. The two Copper lodes (which will be about the last to be reached by the deep Cross-Cut Adit going South) were largely and very profitably worked in tow near-by mines to the East; and the tree lodes intersected were all good Tin lodes, the first being rich. When extended to its full length of half-a-mile, and all the eleven or more lodes cut through at 250 feet from surface, it would be strange indeed if several of theses formations are not discovered to be highly payable. The Tin rock on the old dump is of the most productive West-country type – hard “Tin-capel” and Cornish “Peach,” with a deal of “gossan.” The Tin, also, is fairly coarse.
As stated in detail in the accompanying report upon this Mine, the rare and exceedingly valuable ores Tantalum have been found here; in one or other of the three lodes intersected in the Adit 60 years ago, and – for a continuous distance of some 120 feet – along the line of one of the lode croppings at surface, only 8 years ago. The ores found have been almost chemically pure, and as the value of this metal is somewhere around £2,000 per ton – and as i concentrates easily – very small amounts of it would add hugely to this property’s prospective profits from Tin and Copper. From Tin alone – milling a minimum of 3,000 tons monthly or 36,000 tons per annum of say 2 per cent. Tin-Oxide recovery-value, and with Tin itself at say £150 per ton as now, and Oxide, therefore, about £100 per ton gross value – the crude ore would yield just 40 shillings to the ton as broken. Of which one-half would be profit; less Smelter’s charges of say £12 per ton on720 tons of Concentrate. Nett profit, in consequence of £27,360 per annum.
The ore proved in the Adit was of higher grade, and prices of £150 for Metal and £100 per ton for Oxide are low, so the foregoing estimate seems amply justified. The costs per ton – 20 shillings – could not be exceeded for many years under the conditions obtaining.
To provide properly for the laying down of Compressor Plant and small River Power to drive the same so as to extend the Adit to the Southern boundary without delay will run, perhaps, into £4,000. A further £6,000 should be available for driving off on, and for exploring these lodes as intersected. This calls, therefore, for £10,000 to fairly develop the mine above Adit, and £15,000 more should be in reserve to erect the Mill and Treatment Plant at a later date to crush 3,000 tons monthly, and to leave a margin.
Within 16 months, profits, at the rate of over £27,000 per annum (on the basis named), should be accruing. The tonnage – year by year as the many known lodes were being opened up – should increase rapidly, as should the profit – pro rata – from the ores milled upon the larger tonnage.
During the 18 months or two years development period, the installation of a small Treatment Plant – say 5 stamps, tables and vanners – should bring in a minimum nett revenue of from £500 to £800 monthly from the better class ores, the figure varying with the price of Tin. This Plant, moreover, would be of the greatest use in gaining data for the best system of Treatment of the ores broken from the various lodes, and (by frequent assaying of the Concentrate won) determining upon which of these lodes the most payable values in the ore of Tantalum exist.
The Lease is for 30 years (a longer tenure can be, no doubt, obtained) and the yearly rent is £30, merging into a Royalty of but 2½ per cent on the mineral sold.
These terms – barring the short length of tenure which can be remedied – are unusually liberal.
THE PENHALE MINE.
This property lies 3½ miles North from Liskeard, and the Mineral Railway from the Seaport of Looe – distant 10 miles – passes through the Sett. It embraces 135 acres of arable and pasture land – with a good farmstead – surrounded by moors, and covers one small and four big lodes for about five-eights of a mile along their strike from East to West – see Plan.
The Sett extends alone the Western continuation of Caradon Hill, sloping (steeply at the Eastern end0 to the South. It lies about 1¾ miles S.W. from the old Phoenix Mines – in the strata – which sold Tin and Copper (four-fifths Tin) to the value of over Two and a Half Millions Sterliong, at great profit. Among the 5 lodes named, the Penhale sett covers the Western extension of the principal West Caradon and South Caradon lode, which was so enormously productive and highly profitable in these two mines, about 1½ miles to the East. West of the Great Cross-course, this lode is Tin-bearing right up to surface in the denuded granite – to the East, where partly overlaid by the slate it was Copper-bearing to the depths attained.
Due to it being farm land – reclaimed from the moors generations since – no mining has been permitted upon Penhale Sett until recent times, or except only on the most northerly lode 70 to 80 years ago, and in respect, of course, of the usual “fittings” and “furrowings” along the surface perhaps centuries old, and of very great extent.
Geology, Lode-structure, etc.
A distinctive feature, and a highly valuable indication as regards permanency and mineralisation of the Penhale lode-system (see plan) is that the line of contact between the clay-slate and the granite runs through this property. The South Lode, indeed, fills the contact-fissure - to a certain depth – at various points for about half-a-mile. At 50 to 60 feet depth – vide cross Sections – the overlying slates dip more flatly southwards, and the lode (like the other four) goes on down into the underlying granite. This South or Contact |Lode is at times 20 feet wide in payable ore quite close to surface – and is both Tin and Tungsten-bearing; the two matrices, however, being widely distinct and of differing ages. The lode proper is a re-silicified, coarsely –crystalline granite – approaching a “greisens” – carrying quite coarse Tin Oxide of resinous character and of great purity. The recovery-values from it vary from a few pounds up to a hundredweight or more per ton over considerable widths; 5 to 8 feet and upwards. Very rich ore – up to 25 per cent. Tin – is often found in veins and stringers several inches in width and at less than 60 feet from surface. No pyritic matter or base metals being present, this Oxide concentrates with but small loss and the resulting product assays 70-71 per cent. Tin Metal.
The lode in question - originally Tin-bearing – has been re-opened by some later earth-movement, and into the fissure-cavities of the Tin ore so formed has come further Silica carrying the ores of Tungsten, Wolfram and Ferberite, but no further Tin. These hard, white-quartz “lenses” carry angular fragments and sometimes huge “prism” crystals of the above named minerals, of from several ounces to many pounds in weight – carrying as high as 73 per cent. and more of Tungston Oxide. No Wolfram or Ferberite of equal coarseness and purity have been found elsewhere in Great Britain.
The 4 other lodes traversing this property – vide Plan – all lie in the granite to the immediate North of the Contact. They are all four purely Tin-bearing – of the usual “Tin Capel” and “Peach” matrix – and three of them are of large size: lodes, apparently, of from 10 or 12 up to 20 feet and more in width from the indications present.
The whole area of what is now a field of several acres was, until recently, a connected series of vast, elipitical pits and excavations along the “backs” of these lodes – down to about 40 feet or more in depth, or to water-level. Some of these excavations – in an adjoining field – are yet extant.
Work done and Operations proposed .
In the forties and earlier of the past century, the most northerly of the big Tin lodes was worked down to a considerable depth, and (so say the records) “huge quantities of Tin were returned.” Due, probably, to a slump in price or to difficulties with the landowner, work came to an end. In the sixties, however, when the near-by Caradon copper mines were employing about 4,000 men at great profit, a Deep Cross-cut Adit was driven a quarter of a mile into the hill – northwards – near the Eastern boundary. All five lodes were cut through, and they were all proved to carry Tin and Copper – but mostly Tin. A shaft was sunk over 300 feet upon the line of this Adit – but going much deeper – upon one of these lodes, and in 1862 it was producing “rich Green Carbonate mixed with Oxide of Copper.”
No work was done at Penhale for many years until, in 1909, a small Syndicate spent £1,700 equipping and sinking a Main, Vertical, 3-department shaft at the Western end of the property – vide Plan and Section. They got down to 100 feet, but had no further funds with which to sink or cross-cut. In 1916, the present writer took up the Sett and has worked and prospected it at intervals from that times onwards, spending, all told, about £3,500 of his own and friends’ money.
This expenditure – for the most part – has been on the South or Contact Lode, near the Main Shaft just spoken of. Two small shafts – 250 feet apart – were sunk on this lode to about 60 feet depth, and levels driven underground – see Plan and Sections. These various workings exposed ore-bodies up to 21 feet wide of payable value, and of up to 8 feet and more of quite high values of Tin. At the same time, the aforesaid quartz – lenses of Tungston ores were opened up.
Ore Reserves.
About 4,000 tons of ore are “exposed” above these workings and on the dumps – and ill show average recoveries of perhaps 1½ per cent. Tin Oxide of great purity. This ore can be at once and cheaply handled, and will show a nice profit.
All the surface prospecting and shallow lode-work at Penhale has proved conclusively (a) that the geologic conditions of the slate-contact with a highly-micaceous, coursly-crystallised, and iron –stained granite carrying this seams and veinlets of Tin-Chlorite are ideal; (b) that 4 at least of the 5 lodes are true fissures of great size and persistence along their strike and in all likelihood, therefore, in depth also; (c) that these lodes are well – often highly – mineralised quite close to the surface, and lie at but a short distance apart one from the other at the Western end of the Sett – the granite between them itself carrying Tin in stockwork form, which is at time payable. All this being so, there is and can be but one practical way to now seriously develop these ore-bodies at the cheapest cost and in the least possible time.
The programme so called for is to forthwith re-equip and continue sinking the Main Vertical Shaft another 200 feet, so that – at 300 feet altogether – “settled country,” indicating the upper zone of the big and rich ore-bodies of this district, shall be attained. A Cross-cut then – see Plan – of about 600 feet long, will intersect all 5 lodes, 4 of them, indeed, within a length of about 400 feet. Driving East and West, for the most part Eastwards on these large lodes would then be prosecuted with machine-drills, and quite enormous bodies of ore blocked out, which at this depth should be rich.
Coincident with the foregoing, the Deep Cross-cut Adit at the Sett’s Eastern end should be re-opened, and a main Drainage Adit brought Westwards upon one or other of these 5 lodes – cross cutting to all of them at intervals, while driving same. This Adit – see Plan and Section – would drain the whole length of the property (the heavy “top water”) down to 180 feet or so from surface. Large bodies, also, of very payable if not rich ores would certainly be found upon some of these lodes at this depth, and could be mined cheaply above Adit.
Costs and Profits.
The Development Costs will first run into £5,000 to re-equip and deepen the Main Shaft, and into £7,000, say, for cross-cutting, driving, rising, etc., at that depth when reached. To re-open and bring in the Deep Adit will call for about £5,000 more – a total expenditure over the first 18 months on mining proper of £17,000, Milling and Treatment Plant will later call for some £13,000 or £14,000 and a 5-stamp Battery to treat say 15 tons daily before this Mill is built, would cost £2,00 to £3,000, and would be extremely useful for experimental purposes upon the different types of ores met with. Incidentally, the ores stamped by it – say 360 tons per 24 day month – would be above average grade and might bring in a nett revenue of from £500 to £800 or more monthly; varying, of course, with the price of Tin.
A Cash Working Capital of at least £33,000 is thus required to do justice to this property – but the profits won from it should be very large and also lasting.
Assuming – as a minimum – the mining and milling of 4,000 tons per calendar month, or 48,000 tons yearly of 2 per cent. ore, the yield of Tin Oxide – Concentrate – would be 960 tons per annum. Taking Tin Metal at its now ridiculously low price of £150 per ton, or say £100 gross value for this 70 per cent. product – the value of same is £96,000. Deduct from this say £12 per ton - £11,520 – for smelter charges, and there remains £84, 480. Mining these big and shallow lodes with such cheap power available, the total costs, mining, milling, royalty and overhead charges – amortisation and depreciation included – could not amount to 20 shillings per ton; putting them at that figure, however, and deducting £48,000, there is a nett annual profit of £36,480 – with Tin Metal at £150 per ton. Each pound advance in the price of Oxide would be an extra profit of £960 yearly – less the added Royalty of a few pence payable; and the grade of the ore, as stated, should be higher. The Phoenix Mines averaged well over 2 per cent. recovery value.
This estimate of profit – at Penhale – does not, however, exhaust the subject. It is calculated upon a 48,000 tons per annum basis, whereas – when fully developed this mine, for fifty years or more, should well stand working upon double or more than double this tonnage basis. The nett Profit then (with Tin still £150) would not merely be doubled - £73,000 yearly – but would be still further increased by the lower charges upon the much larger tonnage.
Outside of East Pool when re-opened by her new Shaft perhaps two years hence, the writer believes that there is no other Tin property in Cornwall the assured prospects of which can compare with the foregoing.
The ample Water-Power – 1200 horse at the driest season within a mile of the property – has been elsewhere dealt with – but it will bear repeating.
The Lease is for 63 years – about the longest in the county – and the dead rent is now £100 yearly, merging into a Royalty of one-thirtieth, or 3⅓per cent. The conditions of the Lease are brief and simple.
Briefly reviewing the costs estimated and profits expected from the three properties at to-day’s price for metals, we have these figures :-
NAME OF MINE & CO WORKING CAPITAL YEARLY PROFITS
&c AT TO-DAY’S PRICES
Cash Purchase and Registration, say £8,000 ---
WORKING CAPITAL
The Bodithiel Silver-Lead Mine £25,000 £27,750
The Goonzion Mines ... ... £25,000 £27,340
The Penhale Mine ... ... £33,000 £36,480
________ ________
Total £91,000 £91,570
So that upon a Working Capital Expenditure and other outlay of £91,000 spread over say two years there would be a nett, minimum profit of more than £91,000 yearly – or about cent per cent upon the capital involved.
No note is taken of the sale at Boditiel of the rich or high-grade ores, nor of the Silver-ead ores from the Eastern or Centre Lode, which might well double the above profit; of the sale at Goonzion of any of the highly valuable ores of Tantalum or of Copper ores; nor at Penhale of the sale of Tungten ores – Wolfram and Ferberite – nor of Copper.
Nor is the sale profit of surplus power included.