LONDON — Nyota Minerals has identified two new drill targets next to its existing 690,000 ounce gold resource at Tulu Kapi in Ethiopia.
Nyota holds three licences in Ethiopia. The Tulu Kapi–Ankore and Yubdo Exploration Licences are held for gold exploration, whilst the Yubdo Mining Licence is held for platinum mining. Nyota’s Exploration Licences are located in western Ethiopia in Wellega Province, Oromiya Regional State, in Western Ethiopia, approximately 360 kilometres west of the capital Addis Ababa. The Yubdo Mining Licence is centred on Latitude 9° 10’ 00” South and Longitude 35° 35′ 00″ East.
The company, called Dwyka Resources before it bought Tulu Kapi’s owner Minerva in the summer, says data reveals a possible 300m by 300m northern extension to the 500m by 400m drill grid.
There are also indications of a new North West-oriented anomaly extending for 1.2km, with features indicative of gold mineralisation similar to those at the Tulu Kapi inferred resource.
An additional drill campaign is planned to test these targets in the first quarter of 2010 once the contracted step-out and infill programme has been completed.
Chief executive Melissa Sturgess told ShareCast that the project looks “very, very solid”, with a short-term aim for 1m ounces of inferred resource.
“The nice thing is it’s a hell of a lot bigger than we thought.”
Broker, Ambrian, which owns 5.3% of the business, rates the shares as a ‘buy’ with a target price of 10.8p.
Nyota’s licences overlie a volcano-sedimentary sequence which is part of the Pan-African system and has affinities with the ophiolite suites of the Arabian-Nubian shield which host numerous economic gold deposits. Alluvial gold is widespread throughout the area and a number of hard rock and eluvial deposits have been worked historically.
Tulu Kapi – Tulu Kapi-Ankore Licence Area
Tulu Kapi is the most advanced of Nyota’s gold prospect and the Company recently announced a maiden Inferred resource of 690,000 ounces of gold. Tulu Kapi was mined on a small scale by an Italian company in the 1930s, following which it was later explored by the UN in the 1970s and by Tan Range Exploration in the 1990s. Following a re-interpretation of the structural controls of mineralisation in 2006, a phased drill programme comprising 34 diamond drill holes was completed. Resource modelling and grade estimation has been completed to JORC standards by independent resource consultants Hellman & Schofield. Mineralisation comprises a series of gently dipping gold bearing lode structures demonstrating reasonable continuity. The drill programme and maiden resource covers an area of approximately 600m by 300m occupying a central position within the much larger Tulu Kapi mineralised zone which has been delineated based on gold in soil geochemical survey results and visible evidence of outcropping quartz veins, stockworks and albite alteration.
Nyota has scheduled for reverse circulation and diamond drilling to be completed to upgrade the maiden Inferred resource to an indicated category and to intersect extensions to the Tulu Kapi target to generate additional Inferred resources. The programme is considered a low risk exercise on the basis that soil geochemical anomalies of the same order of magnitude as that coincident with the first 600m of the target that has been drilled extend a further 600m south beyond the current limit of the recent drill programme. In addition, the up dip extensions of gold bearing lodes intersected in drilling have yet to be intersected and the dip direction of these lodes indicates the likely presence of further mineralisation east of the current grid limits.
Other more regional targets have been identified within the Tulu Kapi–Ankore licence including a continuous exposure of quartz veins and quartz float oriented in the same general direction as Tulu Kapi culminating in a former small-scale gold mine operated by an Italian company in the early 1930s.
View of western section of Tulu Kapi Prospect showing drill access roads
[Title? Example of Tulu Kapi drill cross section ]
The Tulu Kapi Exploration Licence comprises an area of approximately 20 square kilometres centred on the old Tulu Kapi gold mine. Tulu Kapi is 9km south of Keley, a small village on the main Gimbi to Dembi Dolo road, 500km west of Addis Ababa. There is abundant water in the region, and good road access and a high power transmission at Keley. The area is surrounded by the Yubdo Exploration Licence Area.
Work done by the UNDP in the 1970s demonstrated anomalous gold grades continue for 1.2km along the shear structure, but Minerva, the previous owner – manager of the Project focussed on only the first 600m section that is oriented northwest-southeast. Thirty four drill holes delineated two dominant hydrothermally altered zones that dip to the southwest. The upper zone which outcrops at surface is over 20m thick, and the lower, higher grade zone is over 10m thick. The scheduled new drill programme will test the grade, depth and strike continuity of these altered mineralised zones as well as other targets that have been identified within close proximity to the main Tulu Kapi mineralisation..
|Tulu Kapi – Significant Down Hole Intersections (at 0.5 g/t cut off)|
|Hole Number||Hole dip||From (m)||To (m)||Length (m)||Au (g/t)|
Tulu Kapi Resource
Following the recent acquisition of Minerva Resources Limited, Nyota has rapidly moved to convert historical exploration drilling results to a JORC compliant resource.
Resource modelling and grade estimation of the Tulu Kapi gold Project located in western Ethiopia has been completed to JORC standards by independent resource consultants Hellman & Schofield. Estimation was based on all verifiable data collated from two drilling campaigns comprising 34 diamond drill holes.
|(g/t Au)||(Mt)||(g/t au)||(oz Au)|
Table: JORC compliant Inferred resource estimates at different cut –off grades for Tulu Kapi
All assay results were generated by certified laboratories. Drilling, sampling, chain of custody procedures and data collection and storage have all been independently verified.
The maiden resource has been generated within the central Zone of Tulu Kapi over a strike length of only 500 metres and over a width of 400 metres. Drill traverses were spaced at approximately 80 metre intervals and individual drill holes were sited at 80 metre spacings along each traverse. Drill holes were inclined at an average angle of 50 degrees in an easterly direction to achieve a notional intersection perpendicular to the assumed dip of mineralisation.
Guji, Gudeya Guji and Dina – Yubdo Exploration Licence Area
Three priority targets have been identified within the Yubdo Exploration Licence: Guji, Gudeya Guji and Dina. [In addition, reconnaissance exploration has identified a number of other target areas within the Yubdo Exploration Licence. The majority of these targets have been identified by soil geochemical surveys with varying degrees of follow up ranging from trenching to drilling. In the majority of cases, exploration has demonstrated potentially economic gold grades and widths warranting more detailed exploration.] Recent completion of ground geophysical surveys across the Guji Prospect have been sufficiently encouraging to suggest that this particular target is drill ready and may be scheduled in the current drilling campaign to start at the end of the rainy season.
Yubdo Exploration Licence; Geology
Guji is the most promising of the targets in the Yubdo Exploration Licence, with an indicated strike length of 1,200m supported by a coincident gold in soil geochemical anomaly and both a trench intersection returning a grade of 9.6g/t Au over 68.5m and a borehole intersection returning a cumulative grade of 3g/t Au over 17m. Nyota has commenced exploration and has completed geophysical surveys over the 1,200m strike length which has defined a linear structure expected to be coincident with mineralisation previously intersected during a scout drilling programme.
Guji Prospect Gold in soil geochemical anomaly
At Gudeya Guji surface mapping has identified an outcropping quartz vein extending 120m. Peak rock chip sample grades achieved include 8.7g/t Au. Peak trench intersections over the same vein outcrop returned a value of 2.8g/t Au over 6.0m. Three scout drill holes intersected two quartz veins over a strike length of 200m.
Photo: Visible gold in quartz vein drill core
Nyota has a team of 4 Ethiopian geologists and 2 British geologist and is building a portfolio of assets at various stages of evaluation. Systematic reconnaissance and follow-up exploration is carried out on the licence areas. In addition to the Guji prospect area, the Dina, Chago and Keley targets are subject to follow-up investigation within the Yubdo Exploration Licence area.
Nyota, through its subsidiary Golden Prospect Mining Company (“GPMC”), owns 51% of Yubdo Gold and Platinum Development Plc (“Yubdo Platinum”). Yubdo Platinum is the sole platinum producing company in Ethiopia. It is a small scale operation, currently producing approximately 100 ounces of platinum a year.
In 2001, GPMC entered into an incorporated joint venture with a local entrepreneur, Mr. Benti Tasissa (47%), to mine the Yubdo platinum deposit. In May 2005 the Mining Licence was transferred to Yubdo Platinum, with obligations to investigate modern mining methods and the process flowsheet for the treatment of platinum bearing laterite resources overlying the Yubdo Ultramfic Complex. In addition, GPMC was required to complete an environmental review, resource definition and carrying out further metallurgical testwork The Mining Licence covers 27.26 sq km within the Yubdo Exploration Licence which is 100% held by Nyota. The remaining 2% of Yubdo Platinum is held by Dr Kebede Belete. Nyota through its subsidiary Yubdo Platinum and Gold Development Company (“YPGD”) has recently submitted an application to the Ministry of mines for conversion of the existing Mining licence to an Exploration licence with the express purpose of undertaking detailed exploration to identify any potential hard rock source for the known lateritic and alluvial platinum mineralisation.
Location, Access and Infrastructure
The Yubdo Mine is 520km almost due west from Addis Ababa. The road is tarred to Gimbi (460km from Addis) and the remainder of the road is gravel. Yubdo village and the mine site have recently been connected to the grid and a digital telephone centre is under construction in the village.
Mining and Processing
Historically, approximately 2,700 kilograms of platinum have been produced at Yubdo by hydraulic mining, mostly during the period 1926-1941 but with small-scale production continuing to the present day. The mining took place in two principal pits, the Main Pit and the Deressa Pit, totalling about 3.3 square kilometres in area. The average thickness of laterite mined was reported as 10m equating to a total volume of 30 million cubic metres at a recovered grade of 0.090 grams per cubic metre.
The present operation, exploiting resources on the western margins of the Main Pit, is based on two 2.5m benches cut into laterite ore which is mined by hydraulic excavator and transported to the adjacent washing plant by dump truck. The Pilot Gravity treatment plant currently being commissioned will consist of a high intensity washing unit, and a multi-stage trommel that serves to disaggregate clay-rich particles. Undersize is directed through a Knelson concentrator and then onto a Gemini table. The concentrate is a saleable platinum concentrate. The scale of the former GPMC operation and the quantity of platinum recovered was modest. The complex metallurgy associated with the platinum bearing laterites and the resulting low recoveries has convinced Nyota of the merits of shtting down the small-scale pilot plant and focussing on exploration to locate any hard rock source for the mineralisation.
Whilst the pilot plant programme has been suspended, Nyota will undertake further metallurgical testwork principally to find alternative processing methodologies to improve recoveries of platinum from the large laterite resource. Historic metallurgical test work suggests that the platinum is ferrous, fine grained and associated with clays within the saprolite – laterite.
Recent work by Minerva geologists has led to a re-interpretation of the mineralising geology at Yubdo and an exploration programme has been proposed to confirm the presence of platinum group metals in ultramafic rocks making up the Yubdo Complex where both the mineralogy and metallurgy of fresh ore is expected to be simpler than that associated with laterites and accordingly recoveries will be improved.
Concentrate and Sales
Minerva exported small quantities of platinum concentrates quarterly produced from the operation of a pilot plant. . The concentrates were couriered to London for refining at Engelhard refineries. The concentrate graded 55-73% platinum and 2-5% gold, with no other significant payable metal.
In 2006 Minerva carried out a programme of pitting over the ridge above and to the southwest of the present small-scale saprolite – laterite mining operation southeast of Yubdo village, in order to estimate the resource in this small area. Thirty pits were completed on a 60m x 60m square grid covering an area of 420m x 240m. Each pit was hand dug at a nominal 75cm diameter down to decomposed bedrock encountered at an average depth of about 10m. Channel sampling at one metre intervals down the side of the pits returned platinum values ranging up to 1.8 g/t Pt, with acceptable repeatability of duplicate samples suggesting that conventional sampling and assay procedures are effective for establishing the total platinum resource.
Based on the results of the pitting, GPMC has used a polygonal method to estimate a resource of 23,760 ounces (793kg) of platinum in 1,470,000 tonnes of laterite material with an average grade of 0.54g/t platinum within the limited area covered by the pitting programme. Importantly, the average grade of the laterite below a barren 1.5m soil layer was 0.82g/t platinum. The pitting programme also indicated that both laterite thickness and platinum grades are lower over the ridge area than on its flanks. Geological mapping shows that potentially mineralised laterite extends along strike for several kilometres on the Yubdo ultramafic intrusion. The ease of mining and potential for further platinum bearing laterite resources within the licence area provides Nyota with the motivation to undertake further metallurgical testwork on the laterites to improve platinum recovery.
Mapping of bedrock exposed in the pitting and in outcrop shows fractures containing quartz-carbonate with pyrite in the form of boxworks and planar fracture fillings occurring in zones trending east of north with generally steep westward dips, cutting the serpentinised dunites and pyroxenites of the Yubdo Ultramafic Complex. Pit sampling shows PGM values in this material relative to fresh rock which support the contention that PGMs are concentrated by hydrothermal action associated with zones of fracturing.
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