Albert Silver Mine

The history of the Albert (Silver) Mine Ltd. 1885 – 1893

The farm originally belonged to Christiaan Joubert, who in 1892 was the Minister of Mines in the government of the South African Republic. In 1885 Alois Hugo Nellmapius discovered silver bearing ore on the farm and subsequently purchased the farm in order to exploit the minerals. He named the mine after his eldest son Albert.

It has not been possible to establish when the company was floated, however it must have been sometime around 1886-7. The prospectus for the Victoria Regina Silver Mine mentions the floating of the Albert Mine some 12 months before1.

The original directors were Isaac Lewis, Samuel Marks, F. Clench, Lewis P. Ford, Carl Jeppe, T.W. Beckett and J.P. Hoffmann. It seemed strange that Nellmapius was not listed as one of the original directors, however, he had certainly became one by around 1889.[1]

Alois Hugo Nellmapius

Alois Hugo Nellmapius circa 1889….
founder of the Albert Silver Mine

In April 1890 Lionel Phillips, one of the partners of H. Eckstein and Co., reported to Alfred Beit that:

Mr H. Jennings visited the Albert mine and was impressed with the immense body of the lode, but will express no opinion pending the results of assays. He says he has never seen such a complicated lode, a great variety of metals apparently being locked in the same vein… [2]

Albert Silver - Mr Jennings took average samples from all parts of the mine and the assays return is only about 4 to 5 ozs of silver. The rock is extremely hard and expensive to mine and Mr Jennings’ brother thought that in such a mine at least an average of 35 ozs. would be required to return good dividends. There appears to be rich streaks in the vein, which contains up to 200-300 ozs. of silver per ton, but as the size of these is not determined nor the vital question as to whether they run regularly or course erratically about the lode, it is impossible to estimate whether any portion of the lode can be worked by itself and made to pay.[3]

The original capital of £9,600 was too small for the venture and several additional loans amounting to £24,000 were raised. It was found necessary to raise the share capital by £50,000; in part to cover the loans and this was done on the 7th January 1888. A further issue of 50,000 shares on the 19th July 1890 increased the capital from £50,000 to £100,000.[4] Again on the 14th September 1893 a notice in The Transvaal Mining Argus states that the shareholders at a special general meeting were to consider raising the capital of the company to £200,000.[5]

In January 1891, J.B. Taylor – partner with Eckstein, but based in Pretoria – wrote to Eckstein that it appeared that the main shaft had been badly placed in relation to the ore body and that after consultation with engineers it had been decided by the Board of the mine to sink the shaft to 100 metres without carrying out further development.[6]

 

In the research it has been determined that the consulting engineer, Mr M. Eissler, was appointed in the latter half of 1891.[7] The mine manager in 1892 was H.B. Bunkell, who had been manager at the Oriental Gold Mining Co. in Barberton.[8] It is not known if he replaced anyone or if he was the first manager.

It seems that the early life of the mine and its disastrous management and development led to its demise in the early part of 1893. The deposit was proven by shafts, winzes and drives over a distance of 416 m. and the mine was developed with two shafts going to a depth of 46 m and the main shaft to a depth of 65 m, where a third level was developed. It was planned to sink this shaft to a depth of 122 m, but this was probably not carried out. Drives were put in between these shafts and they extended beyond the shafts.  Use was made use of a 25mm diamond coring drill to prove the extent of the deposit, which was early use of such technology.[9] It would appear as if management intended the mine to produce for a very long time, because they erected iron headgear at both surface shafts, coupled with a 20 head stamp battery and a treatment plant. In 1905 the mine was surveyed and a plan drawn, It is possible that the erroneous dates for operation of “to 1905” stem from the date of this plan.[10]

Albert Silver Mine

Source: van Zijl, JSV, A Geological-Geophysical Investigation of the Albert Silver Mine North of Bronhorspruit, Transvaal, Bulletin 43, (Pretoria: Geological Survey, 1965)

In May 1892 a report in The Transvaal Mining Argus describes the discovery of a rich lode of ore “carrying pure native copper”, and that the battery was due to arrive shortly for the crushing of the argentiferous rock.[11] By November the same paper was stating that the erection of a 10- stamp battery was nearing completion.[12] However, another source states that a 20 head Sandycroft battery was erected and an ore dressing plant included scoular tables, frue-vanners, continuous bed jig and hydraulic separators.[13] The ore dressing equipment was only brought into service towards the end of 1892, some five to seven years after the deposit was found and the Syndicate formed.[14]

Even at the time of the plant being commissioned the management of the mine were only planning to treat 50 tons of ore per day.[15]  By October of 1892 the share value had dropped to 16 shillings. In December the concentration plant was commissioned[16] and later in the month, the Syndicate was talking of planning to erect a smelting plant rather than ship the concentrates to Europe for smelting.[17]

In January 1893 a report appeared in The South African  Mining Journal :

A bar of silver, stated to be the first ever produced on the African Continent has just been brought into Johannesburg from the Albert Silver Mines by Mr Eissler, the consulting engineer to the Company. The length of the bar is 10 inches, its width 5 inches, and its depth one inch. Its weight, as certified by the Mint Authorities at Pretoria, is 298.30 ounces, and its fineness .944. Mr Eissler states that already 100 tons of concentrates have accumulated, of an average assay value of from 80 to 130 ounces of silver to the ton.[18]

Two months later, in March 1893, the same newspaper was stating that the concentration process seemed to be a success, and that specimens of smelted ore had recently been given to the State President.[19] Barely two months after that report the mine announces that it is closing down.[20] Clearly incompetent management, and the apparent lack of ore at surface to treat, were significant factors in the closure. Virtually all of the capital of the Syndicate was used in the purchasing of machinery and equipment to process the ore and in developing the mine, i.e. shafts and drives, leaving little as working capital. As was indicated earlier in this section Alfred Beit writing to the H. Eckstein & Co., regarding the Albert mine was clearly worried about the lack of productive mining despite the huge expenditure of capital.[21] In a scathing attack in an article in The South African Mining Journal of 27 May 1893 the Editor wrote:

… At few properties have such large amounts of working capital been so recklessly squandered, and at few, have the evil effects of incompetent management been so convincingly exhibited. …. No excuse can be made for the directors. They were given a free hand by shareholders and, instead of proving the mine they have only succeeded in demonstrating their own incompetence.[22]

It seems that management forgot the one basic rule of mining: remove ore, at the same time as you develop, to make the venture pay.

There are several sources in the literature which state that the mine ‘was discovered in 1885 and continued working intermittently until 1905’… or ‘continued working intermittently over a period of 14 years until 1905’. It has not been possible to establish the original source of these dates, but they may have been from the early circa 1905 geological reports. Many of the incorrect dates in the modern reference works on South African mineralogy and mining have their origins in such reports. It is possible that after the Anglo Boer War that the Albert mine was worked on tribute until about 1910.[23] It is more than likely though, given the nature of the ore, that the mine was last worked in 1893. A report in The Standard and Digger’s News in 1893 would indicate that the mine was in serious financial difficulty. At the time it had an overdraft of £ 21 000 – underwritten by the directors – but the company was clearly short of working capital.[24] The operation closed as a working mine in May 1893.[25]

[DETAILS EXTRACTED FROM AN UNPUBLISHED Master of Arts DISSERTATION BY GRAHAM REEKS, UNISA, 2011]

The Albert Silver Mine – Past Work by Lerama

The Albert Silver Mine is a polymetallic deposit comprising known concentrations of Cu-Pb-Zn-Ag-Au-U-F within a set of sub-parallel quartz-hematite veins occurring within the fine-grained apical phase of the Bushveld granite. It was discovered in 1885 and was mined continuously up to 1893. It occurs on the farm Roodepoortjie 250 JR about 80 kilometres east-northeast of Pretoria. Lerama was granted a prospecting permit over this and surrounding farms, Welverdiend 249 JR, Silver Hill 253 JR, Hartbeestfontein 441 Roodepoort 439 JR and Leeuwfontein 248 JR (Figure 1).

albert_silver_mine_2

Figure 1 : Licence holdings of Lerama and the location of the Albert Silver Mine.

Between 1885 and 1893, about 740 m of development was carried out at depths of 21, 46 and 76 m from 3 shafts, and an estimated 20 000 tons of ore grading 1.140 g/t Ag and 10% Cu was produced from development and mining. An ore dump, containing some 1 000 tons, and a waste dump, containing approximately 5 000 tons were left behind when operations ceased in 1893. Assays of dump material report isolated samples up to 400g/t Ag and 0.48% Sb.

In late 1951 into 1952 four inclined boreholes were drilled into the Albert lode (i.e. the southern vein system) by Anglo American Corporation’s Gold Division. Mineralisation intersected in boreholes 1 and 3 were assayed, whereas the mineralisation in boreholes 2 and 4 were not thought to warrant assaying.

Figure 2: Geological map of the farm Roodepoortjie 250JR.

Figure 2: Geological map of the farm Roodepoortjie 250JR.

In 1956 scintillometer surveys showed that significant concentrations of uranium (up to 1 kg/ton) are associated with the base and precious metals. In 1959 geophysical surveys were carried out by the Government over the mine and Northern Vein outcrops.

In the period 1978-1980 the property was re-examined as a potential copper-silver-uranium prospect and a further five boreholes were drilled. 

Recent assay results of the ASM dump material:

The results of the 2004 assays, carried out by SetPoint in Johannesburg, are presented in Table 1.

albert_silver_mine_4

Note:

31.1 grams to the Troy ounce (534g/t = 17.2oz/t)

Au is $1660/oz…… Ag is $31/oz ……(so 53oz of Ag have the same value as 1oz Au)

Therefore 534g/t of Ag is 10.1g/t Auequiv

The assays are from samples collected specifically for their mineralized attributes and should not be regarded as a random suite. They show highly variable Ag contents, from 4g/t to a high of around 1800g/t – the average Ag content of the samples is 534g/t, or some 17oz/t. This equates to a gold content of just below 10g/t, which is regarded as high grade in any deposit type.

The assays also indicate that occasional samples contain gold, with 1 sample registering 0.6g/t Au. Copper contents are also variable, with the highest value at just over 9% Cu and an average for all the samples of 1.3% Cu. There would appear to be little doubt that Ag and Cu represent the 2 principal commodities of value at ASM. It would also appear that Cu and Ag are weakly correlated suggesting that silver is associated with the sulphide paragenesis at ASM and not the oxide assemblage.

The potential of the area is highlighted with the intersection of borehole RP2, which represents a typical log through the North Vein. Previous exploration work mainly focussed on the veins itself, but never took into consideration the disseminated mineralisation within the alteration zone around the veins.

Borehole RP2 was collared to the south of the north vein (Figure 2) and inclined at a steep angle to intersect vein mineralisation at circa 100m depth.  The borehole passed through fine-grained porphyritic granite before intersecting sporadic quartz veins and pervasive propylitic and phyllic alteration between 50-70m below surface (Figure 3). Intensity of veining and hematitic alteration increased markedly below 70m and a well developed zone of Cu-Pb-Zn-Ag-U mineralisation was intersected between 85-120m depth. It has to be noted that none of the boreholes were ever assayed for gold. Vein orientation is subvertical, although occasional zones of brecciation/vein stockworking occur. Between 100-200m depth the core revealed a fairly complex mixed zone comprising both fine-grained and coarse-grained porphyritic granite, suggesting the presence of a contact zone similar to that documented on surface. Sporadic mineralisation occurs throughout this contact zone (Figure 3), but then diminishes below approximately 190m depth. Below 200m only coarse-grained porphyritic granite is present, and this rock is typified by only incipient deuteric alteration, few veins and no mineralisation. It is apparent from this, and other boreholes logged that while mineralisation is, at first glance, apparently related to sub-vertical veins and their associated wall rock alteration, on a broader scale it is distributed along a sub-horizontal zone represented by the contact between the fine-grained granite “roof” and underlying coarser-grained granite.  Consequently, at the Albert Silver Mine veins do not penetrate to great depths within the granite, but appear to be localized in a sub-horizontal zone, that could be up to 40 metres thick depending on the grade cut-off applied (Figure 3), in the apical portions of the granite body. This observation is similar to the distribution of polymetallic sulphide mineralisation at the Spoedwel Mine in the Marble Hall district and has important implications for the exploration of other polymetallic deposit types in the Bushveld.

Historic exploration work only focused on the farm Roodepoortjie 250 JR. Regional soil geochemical work carried out by Anglo American, however, shows that the mineralised zone of the North Vein continues to the west onto the farm Welverdiend 249 JR and possibly to Roodepoort 439 JR and Leeuwfontein 248 JR.

Figure 3 : Borehole log and assays for RP2, north vein, Albert Silver Mine

Figure 3 : Borehole log and assays for RP2, north vein, Albert Silver Mine

The vein systems including the alteration zonation and the sub-horizontal mineralised zone represented by the contact between the fine-grained granite “roof” and underlying coarser-grained granite requires further exploration to increase the already existing resource. During the time of exploration by Anglo the IOCG model did not exist and the polymetallic Albert Silver project has never been systematically investigated for its gold and uranium potential.

[FROM A REPORT TO LERAMA RESOURCES Ltd BY MSA Geoservices; Author: RUSSELL BAILIE, 25th August, 2008]

The Albert Silver Mine – Recent Work by Lerama

  1. Structural setting of the Albert Silver Mine

Three types of veins (in decreasing order of frequency) are recognized namely quartz, mineralized Fe-oxide and granitic veins. The veins form two dominant sub parallel vein systems linked by an inclined subset forming a “Z” shaped distribution. The two main sub-parallel veins systems have total strike lengths of ~3.5 kms with each being ~2kms long arranged in an en-echelon fashion. The inclined linking sub-vein set has a length of ~500m and is not well exposed. The mineralisation veins (Fe-oxide rich zones) in each of these zones is shorter with exposed lengths of between ~150m-~400-500m. At the thickest areas it is estimated that mineralisation is seen over maximum widths of ~20m. The mineralization is not continuous but distributed across multiple veins but probably more typically 5-10m. Analysis of the orientations of the various types of veins, localized kinematic indicators and the overall distribution of the veins suggests they resulted from a left-lateral strike-slip transtensional fault setting. The vein genesis, faulting and jointing were broadly synchronous with intrusion of the granite and late stage fluid fractionation from the granite.

Figure 4: Structural study of the Albert Silver Mine and environs (from a Report to Lerama by G. Grantham, Council for Geoscience, 2012)

Figure 4: Structural study of the Albert Silver Mine and environs (from a report to Lerama by G. Grantham, Council for Geoscience, 2012)

  1. Geophysical and Remote Sensing Interpretations

Work by the Council for Geoscience suggests that zones of alteration and magnetic lineaments can be used to assist in the targeting of mineralization on Roodepoortjie, and the positioning of drill holes.

Figure 5: Remote sensing and geophysical interpretation of the Albert Silver Mine and environs (from a Report to Lerama by J. Cole, Council for Geoscience, 2012)

Figure 5: Remote sensing and geophysical interpretation of the Albert Silver Mine and environs (from a report to Lerama by J. Cole, Council for Geoscience, 2012)

Geophysical methods applied include ground magnetics, gamma ray spectrometry, time domain electromagnetics (TDEM), induced polarization (IP) and frequency domain electromagnetics (FDEM). Ground magnetics and spectrometry were used as rapid aerial extent mapping techniques. The TDEM and IP methods were carried out on a target area selected based on magnetics and spectrometry.

A total of 132.5 line km of magnetics and radiometrics were completed initially before selection of the IP/TDEM target was done. Predominantly east-west magnetic fabric of reduced magnetic field intensity possibly indicative of shearing and hematization were also mapped.

The extent of the fine grained and course grained Verena Granites were inferred from the radiometric data. Radioelement ratios Th/U and Th/K were used to infer areas of potential hematization that could be associated with mineralization.

Figure 6: a. Uranium gamma ray spectrometer map; b. Model chargeability-depth sections; c. TDEM chargeability across the Albert Silver Mine and environs (from reports to Lerama by J. Cole, Council for Geoscience, 2012 and E. Chirenje et al., Council for Geoscience, 2013)
Figure 6: a. Uranium gamma ray spectrometer map; b. Model chargeability-depth sections; c. TDEM chargeability across the Albert Silver Mine and environs (from Reports to Lerama by J. Cole, Council for Geoscience, 2012 and E. Chirenje et al., Council for Geoscience, 2013)

Figure 6.a

 

albert_silver_mine_9

Figure 6.b

albert_silver_mine_10

6.c

IP and TDEM results showed vertically dipping zones of high chargeability that extend at depth. These chargeable zones where coincident with high resistivity are probably due to the presence of metallic sulphides in sheared and silicified granites.

The chargeable zones extend laterally eastwards and westwards along the known ASM mineralization. Potential mineralized targets with coincident high chargeability, high resistivity and high decay constant were identified to the northwest and the northeast.

  1. Evaluation of historical drill-hole information at the Albert Silver Mine

Boreholes drilled in the period 1950-1980 by the Anglo American Corporation have been digitized and evaluated. These data will contribute to the selection of new drill targets and in the evaluation of a resource at ASM.

albert_silver_mine_11

Figure 7: Drill hole profiles and logged lithology for historical holes drilled at Albert Silver Mine

Figure 7: Drill hole profiles and logged lithology for historical holes drilled at Albert Silver Mine

Figure 8: The fine grained porphyritic granite host rock to mineralization on Roodepoortjie and surrounds.

Figure 8: The fine grained porphyritic granite host rock to mineralization on Roodepoortjie and surrounds.

 


[1] CS Goldman, The Financial, Statistical and General history of the Gold & other Companies

of Witwatersrand, South Africa, p. 214.

[2] Archive of H Eckstein & Co, Vol. HE 149, Letter book of L Phillips, 18 April 1890, p. 190.

[3] Archive of H Eckstein & Co, Vol. HE 149, Letter book of L Phillips, 25 April 1890, p. 192.

[4] CS Goldman, The Financial, Statistical and General History of the Gold & other Companies of   Witwatersrand, South Africa, p. 214.

[5] ‘The Albert’, The Transvaal Mining Argus, 14 September 1893.

[6] Archive of H Eckstein & Co, Vol. HE 189, Letter book of JB Taylor to Johannesburg office, 31 January 1891, p. 76.

[7] ‘Albert Silver Mine’ The South African Mining Journal, Vol. 1, 14 November 1891, p. 113.

[8] ‘The Albert Silver Mines’, The South African Mining Journal, Vol. 1, 13 August 1892, p. 810.

[9] Ibid.

[10] Plan of the underground workings in JSV van Zijl, A Geological-Geophysical Investigation of the Albert Silver Mine North of Bronhorspruit, Transvaal.

[11] ‘Albert Silver’ The Transvaal Mining Argus. 27 May 1892.

[12] ‘Albert Silver’ The Transvaal Mining Argus. 4 November 1892.

[13] ‘The Albert Silver Mines’, The South African Mining Journal, Vol. 1, 13 August 1892, p. 810.

[14] Ibid.

[15] ‘Albert Mine’ The South African Mining Journal, Vol. 2, 2 October 1892, p. 56.

[16] ‘Albert Silver Mine’ The Standard and Digger’s News, 17 December 1892.

[17] ‘Financial and General Notes’ The South African Mining Journal, Vol. 2, 10 December 1892, p. 182.

[18] The South African Mining Journal, Vol. 2, 21 January 1893, p. 259.

[19] Ibid, Vol. 2, 11 March 1893, p. 372.

[20] Ibid, Vol. 2, 27 May 1893, p. 545.

[21] Archive of H Eckstein & Co, Vol. HE 59, Letter book of Werner Beit & Co to H Eckstein & Co, 22 April 1891. p. 5.

[22] The South African Mining Journal, Vol. 2, 27 May 1893, p. 545.

[23] LJ Robb, et al. ‘The Albert Silver Mine Revisited: Towards a Model for Polymetallic Mineralisation in   granites of the Bushveld Complex, South Africa.’ 1994, Expl. Mining Geology, v3, 247-262.

[24] ‘Albert mine’ Standard and Digger’s News, 16 September 1893.

[25] Albert Silvers’, Standard and Digger’s News, 25 May 1893.

 
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