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SEMAFO NABANGA DEPOSIT (0.66Moz) | Burkina-emine
Annual Archive


15 February 2016


Project Location and Access

The Nabanga Gold Project is 100% owned by Semafo Inc. It is located within the Company’s Nabanga exploration permit in the south-east of Burkina Faso.

Nabbanga is accessible from Ouagadougou via Fada N’Gourma and

Kompienga towns by a 250km paved road and further 15km of gravel road to site.

Infrastructures are available with Lake Kompienga situated at 5km and Hydro-power line at 10km.


.  The Nabanga Prospect has been subject to artisanal workings.

.  Mt Isa Metals Ltd is an Australia-based resource company focused on exploration. By May 2010 the Company had assembled a large portfolio of gold exploration permits in Burkina Faso.

.  ORBIS started active exploration in Burkina Faso in late 2010.  In Burkina Faso, its strategy was acquiring projects with outcropping quartz veins and/or artisanal gold workings.

.  Orbis first exploration campaign in Burkina Faso was 2010-1011.

.  Early 2011, near surface high grade gold mineralization was hit by Mt Isa Metals in RC drilling at the Nabanga prospect. The Nabanga gold discovery was announced by Mt Isa On January 20, 2011.

.  September 22, 2011, Mt Isa Metals has revealed two new high grade gold zones for the Nabanga project at the Central Zone (500 metres strike length) and the North Zone (600 metres strike length).

.  In August 2012, the Company formally changed name to Orbis Gold Limited (ASX: OBS).25 September 2012, ORBIS Gold announce an initial maiden resource for its Nabanga gold deposit with 0.66Mozs @ 6.5g/t Au of Inferred Mineral Resource.

.  During the year 2012 the Company commenced scoping studies to define the mining and metallurgical characteristics of the Nabanga deposit. The studies are in progress for assessing combined open pit and underground development.

.  September 25th 2013, Orbis Gold confirms extension of high grade gold mineralization below the 200 metre limit for the Resource.

.  February 10, 2015: Following a takeover, Orbis Gold board unanimously accepted Semafo offer revised offer price of a $0.713 best and final.

 Project Geology

The Nabanga deposit is located on a tong of the Lower Proterozoic or Birimian greenstone belt in the South East Burkina Faso.

Nabanga structure extends over a total 9km strike length within altered and quartz-veined granodiorite intrusive host. The granodiorite is in contact at the north with greenstone rocks package. Gold mineralization is predominantly developed within a single laterally extensive fault structure that exhibits a steep north-west dip. Secondary sub-parallel and cross cutting faults have been mapped in the vicinity of the ore body.

Gold is associated with quartz veining and a distinctive alteration zone. A persistent quartz vein is developed within the fault plane varies in thickness from an estimated 0.5m to 3.0m true width. Wall rocks adjacent to the central quartz vein are often altered / sheared.

The base of oxidation in the vicinity of the Nabanga deposit is relatively shallow and fresh rock is generally encountered below 14 meters vertical depth.


Nabanga belongs to the “intrusion-related” class of gold deposits. It is a high grade quartz vein associated gold deposit. The deposit has high grade nature and high relative retention of contained ounces at higher cut-off grades. It has excellent potential for development of a long term selective underground mine in conjunction with an initial open pit mine development.

The deposit can extend to substantial depths reflecting the typically deep seated / vertically extensive nature of the host intrusive rocks.


Nabanga gold deposit is a High Grade Gold System, intrusion‐related (granodiorite-hosted). The modeled mineralization occurs within a single, continuous structure of over 2.3km in length, with two minor fault offsets. On average the mineralized structure is 3.2m thick in a horizontal plane, dips between 55⁰ and 70⁰ to the NW. The deposit comprises South Zone, Central Zone and North Zone. A parallel gold-bearing structure is called Nabanga North Lode and has 800m strike length.

The mineralization occurs as high grade shoots in sheared quartz veins and continues down below 200m. A significant proportion of the high grade assays from Nabanga are recorded within the quartz vein. Preliminary thin section indicates that gold is present as gold-tellurides and gold-silver tellurides within fine grained sulphides (predominantly pyrite).

The Nabanga deposit exhibits a gold-silver-tellurium +/- bismuth metal assemblage.

Mineral Resources

 Orbis Gold (ASX: OBS) has reported a maiden Inferred Mineral Resource estimate, JORC compliant of 3.2Mt @ 6.5g/t Au for 660,000 ounces of contained gold (reported above a 0.5g/t Au cut-off grade) for the Nabanga gold deposit. The estimate was completed in September 2012 by Snowden Mining Industry Consultants on behalf of Orbis Gold Limited.

Source: Refer ASX release “Nabanga Gold Project – Maiden Resource” dated 25 Sept.  2012



Tonnes (Mt)

Grade (g/t Au)

Ounces (Mozs)

Nabanga Deposit



3.2 Mt


0.66 Mozs



3.2 Mt


0.66 Mozs

 Summary tabulation of the Nabanga Inferred Mineral Resource reported across a range of cut-off grades is presented in Table below.

 NB: Some of the figures are modified from company public data

15 February 2016

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