Abenab Trend

Location

The Abenab project is located within the Grootfontein District of the Otjozondjupa Region of northern Namibia. The historic Abenab Mine is 32 km north of Grootfontein, within the Otavi Mountainland.

Geology and Mineralisation

Regional Geology

The Abenab project is located in the north-eastern part of Namibia within the Otavi Mountainland region of the Damara Belt. The Otavi Mountainland is composed of carbonates and siliclastic units formed during rifting events of the Adamastor Ocean of the Cryogenian, with the Otavi Group platform carbonates composed of Abenab and Tsumeb Subgroups making up the Damara Supergroup. The Otavi Mountainland was deformed during the Damara Orogeny that folded the Damara Supergroup into east-west trending synclines and anticlines.

 

     Location of Abenab Trend showing Prospect location.

 

 Local Geology and Mineralisation

The Abenab mineralisation is hosted by carbonates of the Otavi Group. The deposit consists of a pipelike karst structure filled with a breccia of collapsed country rocks associated with compacted red muds and cemented by coarse calcite and decloisite-vanadinite concretions. The Abenab pipe lies on a steeply dipping bedding-parallel structural contact.

The lithological carbonate contact is a sheared zone between a massive dolomite and a platy limestone. The Abenab pipe lies on a steeply dipping bedding-parallel structural contact.

The Abenab mine vanadium-lead-zinc mineralisation is in the form of the oxide minerals descloisite (Pb,Zn(VO4)(OH)) and vanadinite (Pb5(VO4)3Cl). The vanadium mineralisation takes several forms including breccia clast infill, fine grain fracture fill, open space crystal growth and clay-filled cavities.

     Geological map prepared by SWA Co Pty Ltd in the 1940s showing the Abenab and Christiana faults.

 

 Abenab Mine cross section showing current resource boundary at 0.2% V2O5 cuttoff (green) and target area for in-mine exploration (red)

History

The Abenab Mine was operated as an open pit and underground mine from 1921 to 1947 by South West Africa Company primarily for the lead-zinc, was probably the largest known and highest grade deposit of vanadate ore in the world.

The initial production was 30 to 80 t of high-grade vanadium ore recovered by blasting and hand-sorting. By 1923 the mine had been developed and was operating at a production rate of 1 000 to 2 000 t per annum.

The pipe was mined to a depth of about 215 m until reduced grades and the flow of underground water rendered further mining uneconomic.

Following the mine closure exploration was conducted by companies including Tsumeb Corporation, Anglo American, Japanese International Cooperation Agency (JICA) and Avonlea Minerals. Work conducted comprised several phases of RC and diamond drilling, trenching and geological mapping. In the period 2011 to 2012 Avonlea drilled nine diamond holes for 2,597m over two campaigns.

Geological Review and Target Generation Study

In November 2018, Golden Deeps (GED) engaged highly experienced and recognised consultancy Shango Solutions (Shango) to conduct a comprehensive geological and drill targeting study on the Abenab Project. The study facilitated the integration of newly acquired historic exploration data from AVZ Limited (formerly Avonlea Minerals Limited).

Shango commenced the study with an extensive search for additional historic data followed by compilation and validation of the exploration data. Historic underground drill holes were captured off old level plans adding to the digital database. As a result, the database has been updated and enhanced providing a robust platform for future exploration work.

New 3D geological models have been generated for Abenab and Abenab West. The addition of underground drill data from old mine plans allowed lithological contacts and faults to be modelled resulting in an improved understanding of the ore zones and the lithological and structural controls on mineralisation.

Resource Estimate Update

In January 2019 Golden Deeps reported an updated JORC 2104 compliant Inferred Mineral Resource for Abenab. The new resource estimate is the result of the geological review and reinterpretation conducted by Shango Solutions. The new resource delivered a 150% increase in total tonnes at a revised cuff-off grade of 0.2%.

The updated JORC Inferred Mineral Resource for Abenab calculated by Shango is:
· 2.80Mt @ 0.66% V2O5 (vanadium pentoxide), 2.35% Pb (lead), 0.94% Zn (zinc)at a 0.2% V2O5 cut-off
o which equates to 18.5kt vanadium pentoxide, 65.8kt lead and 26.3kt zinc.

By lowering the cut-off grade from the previous Resource calculated by SRK, GED has significantly increased the tonnages by 4.1kt vanadium pentoxide, 31.6kt lead and 12.3kt zinc.

Joint Venture

Golden Deeps Limited (Golden Deeps) has entered into a Joint Venture Agreement (JVA) with Hong Kong based metals trading company Generous Metals Company Limited (GMC) to crush, concentrate, refine and sell vanadium product from Golden Deeps’ Abenab Vanadium Project in Namibia.

Under the terms of the JVA, Golden Deeps’ subsidiary, Huab Energy Pty Ltd (Huab), will provide the existing stockpile and tailings from the Abenab Project in to the Joint Venture (JV). The JV will then crush, concentrate, refine and sell the end product.

The JVA represents a very significant milestone in the development pathway at the Abenab Project and is the first step in the Company’s stated strategy to develop a plant at Abenab to treat ore mined from underground. 

The JVA provides a solid foundation to accelerate the development of the Abenab Project with the objectives of delivering stage-one production of vanadium concentrate at Abenab and produce vanadium products in the near term.

In addition to the expected financial benefits from the JV, Golden Deeps will benefit from the experience and knowledge gained in the lead-up to and operation of the JV. The planned 250,000 tpa crushing and concentrator plant proposed for the JV is modular in nature, providing Golden Deeps with the ability to add further modular units should this be required in the future.

The operations of the JV also provide for investment into Namibia along with in-country employment opportunities. The crushing and concentrating of the stockpile and tailings will take place at the Abenab Project site. The concentrate will then be shipped to China for refining and marketing of the end vanadium products, which will include vanadium pentoxide (V2O5) and ferrovanadium.

All activities of the JV in Namibia will be managed by Golden Deeps and all activities in China, including marketing of the vanadium products, will be managed by GMC.

For More information see the Announcement of 8th April 2019
 

Abenab West

The main target of the Abenab West Prospect is the extension and unmined portion of the Abenab West mine. Production figures from Abenab West indicate that 88,000t of vanadium, lead and zinc concentrates were produced from 540,000t of underground ore. The workings extend over 800m of strike and to a depth of at least 380m below surface.

    Aerial view of Abenab and Abenab West mining area. Underground workings at Abenab West are depicted in             black (50ft Level Drive)

Mineralisation

Three styles of mineralisation have been observed by Golden Deeps at Abenab West:

 

    An example of descloizite from Abenab

 

The three styles of mineralisation appear to be closely associated with each other and are often intercalated.

The underground workings at the Abenab West Mine consist of a series of ‘strike drives’ developed on 50ft (15m) spaced levels along a footwall shale contact. Cross-cuts are developed out to the north to access the interpreted ore position. The levels are linked to the surface by the centrally located Malcolm Shaft.

Channel sampling accessible underground development on three mine levels down to the 200ft level as well as open pits and surface exposures, identified wide zones of high-grade mineralisation. The channel sampling spacing of 20m roughly matches the underground cross-cut spacing and provides a high level of sampling detail for the planning of future exploration programmes.

Approximately 500 metres of strike has been sampled at surface and on the 50ft, 100ft and 200ft levels. Almost every channel sample has returned highly anomalous zinc, lead and vanadium mineralisation.

The results indicate the following;

This demonstrates the enormous potential of the Abenab West prospect to generate lead-zinc and vanadium resources.

     Abenab West underground workings

      Dolomite coated with dark grey descloizite (left) and sheared willemite material (right)

Abenab East

The Abenab East prospect is located approximately 5km along strike to the northeast of Abenab. Geological mapping in the area has revealed several exposures of breccia that may represent Abenab type breccia pipes. Exploration in the area has been hindered by transported cover and calcrete. Soil sampling generated several basemetal anomalies but sampling was not effective.

Abenab East is prospective for Abenab style vanadium breccia pipes at the faulted T2/T3 contact.

Abenab East prospect showing breccia occurrences and lead-zinc soil results >250ppm

Nosib Block Prospect

The Nosib Block prospect is centred on a group of old copper workings located approximately 27km southwest of Abenab. The prospect is situated on the northern limb of the east-west trending Nosib anticline. Granite of the Grootfontein Basement is overlain by a sequence of arenaceous sediments of the lower Nabis Formation of the Nosib Group. The arenaceous sediments pinch out against the granite which is interpreted to have been important in providing a suitable trap for mineralising fluids.

The copper mineralisation was mined via a shaft and three levels of underground workings.

In 1995, Goldfields Namibia drilled 25 holes for 824m on traverses 50m apart targeting the arenite pinch out structure. Fourteen of the holes intersected visual indication of copper mineralisation.

Channel sampling along the levels gave a best result of 6m @ 1.51% Cu, 10.59% Pb and 1.12% V2O5. The mineralisation forms a plunging shoot and is open at depth.
 

    EPL3543 location plan showing location of the Nosib Block prospect

Underground channel sampling carried out in late 2013 on three levels of the Nosib Mine showed high grade Vanadium mineralisation associated with copper. As most of the mineralisation is within 60m of surface potential exist for an open cut mine.

The prospect will be drilled following the current drilling programme at Abenab to generate a resource to add to the current inventory.

Plan of channel sampling on level one of Nosib mine (20m Below Surface)

 

Channel ID M from   M to   Interval(m VxO5%   Cu%   Pb%   Zn% 
NOUG0005 5 6 1 6.5 5.19 17.23 0.21
NOUG0006 1 6 5 1.32 1.22 4.99 0.5
NOUG0008 3 6 3 0.69 0.92 3.61 0.67
NOUG0009 0 5 5 1.58 1.61 5.6 0.12
NOUG0010 0 9 9 3.25 2.78 7.8 0.5
NOUG0011 3 4 1 1.27 1.14 3.96 0.03
NOUG0012 2 7 5 1.77 1 3.86 0.05
NOUG0013 0 5 5 1.03 1.46 3.79 0.04
NOUG0014 0 2 2 1.52 1.79 6.08 0.08
NOUG0015 2 3 1 1.55 1.54 4.07 0.07
NOUG0019 0 11 11 0.32 1.36 2.67 0.04
NOUG0020 0 26 26 1.98 1.94 7.27 0.29
NOUG0021 0 28 28 0.46 0.65 3.77 0.16
NOUG0022 0 13  13 0.26 1.23 0.97 0.05
NOUG0023 0 15  15 0.62 0.63 1.63 0.06

Nosib Block Channel sampling results

 

Okurundu

The Okurundu prospect is a small breccia pipe located approximately 2.5km west of the Abenab Mine. The pipe is at the T2/T3 contact along strike from Abenab. Vanadium mineralisation is similar to the Abenab Mine comprising brecciated dolomite clasts with a sparry calcite and clay matrix containing descloizite. The orebody was mined as an open pit and via a shaft and underground development.

The prospect is located on a well defined >250ppm lead-zinc soil anomaly that trends northeast-southwest from Abenab with a broad >100ppm vanadium anomaly to the south and west. The breccia pipe is located within a cutting in the limestone ridge that is caused by cross cutting structures that interpreted to be an important structural control for the pipe. A second area of breccia has been mapped north of the historic mine. A single shaft has been sunk on the breccia but no significant mining was conducted.

The breccia pipes were drilled by Goldfields Namibia Limited. Most of the drilling was focussed on the southern pipe that has been mined with only two holes drilled at the northern pipe that was considered too low grade.
 

     EPL3543 location plan showing location of the Abenab and Okurundu prospect

     

Soil sampling results at Okurundu prospect

Okurundu prospect open pit and surface exposure of breccia