The Akobo project  

   
 

The Akobo Project

 

The Akobo license area covers 250 km2, situated in the far southwest of Ethiopia. In Ethiopian terms it is a lowland area, about 600-800 m.o.s.l., of beautiful, gently rolling savannah landscape, semi-arid with a gentle rainy season June-November, and temperatures reaching 40 degrees C during the hottest, dry periods.

 

Geology and potential resources

Setting:

Akobo is an extensive placer gold region characterized by a Precambrian belt of metamorphic rocks. These rocks constitute the southernmost part of the West Ethiopian Precambrian Greenstone Belt, a southern extension of the Arabian-Nubian Shield, known for many gold deposits, ancient and modern. Large and small bodies of ultramafic rocks characterize the Akobo area. Similar rocks occur along the belt to the north, i.e. at Yubdo, Tulu Kapi, Tulu Dimtu, Baruda etc. Gold is broadly associated with these areas of higher concentration of ultramafic bodies.

The Arabian-Nubian Shield represents a large, under-explored area of Precambrian terrane, and the Akobo area especially so. This area appears to have been unknown to be gold bearing until Italian prospectors investigated the area during the Italian occupation of Ethiopia 1936-41. A French-Norwegian mining company based in Addis 1929-1933 operated the Yubdo platinum mine and had gold exploration expeditions in Beni-Shangul, Wollega and Maji, without noticing any rumor of gold in nearby Akobo. The Ethiopian government, by the Ethiopian Institute of Geological Surveys (EIGS, later renamed Geological Survey of Ethiopia, GSE) investigated the gold potential of the area in the 1980s. ETNO Mining plc acquired an exploration and placer mining license in and started operations in 2007. Shortly thereafter artisanal mining activities escalated rapidly, and today this previously very thinly populated Surma and Anouak people area, has about a dozen mining villages with an estimated population of 20-30 000 inhabitants, coming from all over Ethiopia.

 

Gold mineralization

In addition to the extensive placer gold deposits, three types of bedrock gold mineralization have been identified:

  1. I.            Outcropping quartz veins of considerable size (meter-tens of meters), showing gold values up to >100 ppm. Typically occurring in the Wolleta area within the ETNO Mining license area.
  2. II.            Extensive stockwork of smaller quartz veins (cm-dm) in quartzofeldspathic host rock, with bulk grades of ~1 ppm, as occurring north of Joru village.
  3. III.            High-grade gold mineralization (up to >1000 ppm) in pervasively altered and partially sheared ultramafic rock and metagabbro. The Segele pit area, south of Shama village.

I

The Wolleta quartz veins were RC drilled, in 2015, with disappointing results. The extensive surface outcrops are not reproduced in drill sections. Drilling was directed perpendicular to the regional foliation. The probable conclusion is that the veins crosscut foliation. Observations in artisanal pits in the Joru area support this conclusion, indicating that the main trend of the quartz veins are dipping towards SW. If so, the drilling was mostly parallel to the quartz veins and thus not intersecting.

While being an interesting target, volume potential is questionable and further investigations of this type of gold mineralization have been put on hold. Priority is given to types II and III.

II

The Joru stockwork is sampled and analyzed in several trenches over a strike length of >3 km. Trench 12 is showing a section of 44 m @ 1,2 ppm. RC drilling underneath the trench from the NE largely confirms similar grades. Drilling was, however, routinely directed perpendicular to regional foliation, but later observations have shown that the quartz vein trend is mostly dipping parallel to the drilling direction, thereby probably largely missing the mineralized veins. Several other trenches and RC intersections show similar grades in sections up to 16 m. The potential for a large, low grade ore body seems good. The Joru quartzofeldspathic hosted gold quartz stockwork shows similarities with the Tulu Kapi gold deposit presently being developed 300km further north (http://www.kefi-minerals.com/projects/ethiopia/tulu-kapi).

Detailed mapping of the Joru area is pending. Field work had to stop because of heavy grass cover developing, and for a period security issues, but is planned to resume when conditions are good.

Artisanal miners, mostly near trench 12, working shafts into the quartzofeldspathic hosted quartz stockwork, presently exploit the Joru primary gold.

III

At Segele, artisanal shafts and excavations in coarse-grained mafic-ultramafic rock have combined to produce about 1000 kg gold from a pit of present surface size of about 15x20 m, reaching a depth of about 13 m. The main production period was from early 2015 until early 2016. The average gold content is thus ~100 ppm (g/t), but keep in mind that a considerable part of the pit volume was taken out following two cave-ins, without being processed, i.e. the gold grade of the actually produced material was significantly higher.

The artisanal mining is totally manual. Shafting is done with hand held iron peckers, crushing by hand in steel mortars, and panning with wooden pans, called batea. Mercury/amalgamation is not in use as far as we know, and the soil geochemistry ETNO has conducted supports this conclusion. Government control is good and all gold, at least most of it, is collected locally by the government bank, paying market price. Production numbers and statistics seem fairly robust.

The present knowledge of the Segele mineralization is based on detailed geological mapping; mapping and logging of 67 artisanal pits/shafts; 24 trenches totaling 2573 m; microscopy and Scanning Electron Microscope analyses of 7 samples/thin sections; systematic sampling and chemical analyses of 138 samples from 13 pits; 4 RC drill holes, 2 of which intersects the main gold zone; in addition to information collected from the artisanal miners, the kofari.

  • Gold is coarse to fine grained and highly unevenly distributed.
  • The gold is unusually pure, with no silver or other metals.
  • Platinum group minerals (PGM) are present in interesting amounts.
  • Detailed trenching has mapped a well correlated gold zone extending >230 m to the W of Segele Main Pit, supported also by additional data from artisanal pits, connecting with the Main Pit zone.

 

Plans

The Segele type gold mineralization is presently first priority in the continued exploration activity. This is because Segele represents an immediate opportunity to establish production and revenue.

Developing a working model for the formation, structurally and hydrothermally, is of vital importance and a key to success. Understanding the structural control is perhaps the most important factor at this stage of exploration, and can be the guide to the next bonanza deposit.

The coarse-grained gold and erratic distribution in the gold zone presents a problem in establishing robust grades for the deposit. Large samples are needed. Crushing and milling capacity need to be installed to process large samples.

Extensive trenching has given good control of the surface outcropping of the Segele Gold zone. Drilling is needed to acquire systematic data at depth. The artisanal shafts have given valuable data to allow us to understand the 3D development of the zone, but only at shallow depths. More and better data is needed.