Overview

Mine Type	Open Pit & Underground
Status	Active
Commodities	Copper Zinc Gold Silver
Mining Method	Truck & Shovel / Loader Longitudinal open stoping Pillar mining
Backfill type	...
Production Start	...
Mine Life	...
Snapshot	The Asmara project encompasses deposits, namely Debarwa, Adi Nefas, Gupo, and Emba Derho. According to the feasibility study 2013, the Asmara Project will be mined on three production phases, with total mine life of 17 years. On April 8, 2024, Asmara Mining Share Company (AMSC) has successfully completed its maiden shipment of direct shipping ore (DSO) from the Debarwa deposit (Phase 1A). In Phase 1A of the project, AMSC focuses on extracting high-grade copper from the Debarwa deposit using open-pit mining methods. Once extracted, the ore is crushed, loaded into containers, and transported over a distance of 120 kilometers to the port facility at Massawa.

Deposit type

• VMS

Summary:

The base metal deposits of SGC in the Asmara Project (Emba Derho and Adi Nefas) and Debarwa are examples of volcanogenic massive sulphide (VMS) deposits located in the Neoproterozoic Arabian-Nubian Shield (ANS). The ANS represents a composite granitoid-greenstone belt terrain that straddles the Red Sea and covers much of Eritrea, parts of Egypt, Sudan and Ethiopia, and the western part of Saudi Arabia.

The Gupo gold deposit shares similarities with other shear-hosted quartz-vein related gold deposits that are formed in Precambrian terrains and subsequently modified by tectonic events and nearsurface weathering effects.

All deposits have been subjected to near surface weathering effects such that the base metal VMS deposits exhibit oxidation and remobilization of metals. Typically the surface manifestation of the deposit is a gossan overlying zones of depletion or enrichment in oxide, supergene and transition zones. Primary sulphides are developed at depth.

Emba Derho The Emba Derho deposit appears on surface as a prominently outcropping gossan developed over an area of 800 m by 220 m where it outcrops as a tightly folded unit with northwest oriented fold axial planes and steeply dipping limbs. The sulphide mineralization is hosted within variably but generally heavily sulphide-altered, and moderately sericite-, chlorite-, and quartz-altered predominantly felsic metavolcanic rocks.

The mineralised zones are:
• Gossan (oxide zone).
• Copper-enriched supergene zone.
• Pyritic massive sulphide primary zone.
• Zinc-rich primary massive sulphide zone.
• Copper-rich primary massive sulphide zone.

For the purposes of estimation, four distinct zones of mineralization are recognised. A surface oxide gold-rich zone strongly leached with respect to base metals, a zinc-poor supergene zone, overlying a zinc-rich primary sulphide zone which is in turn underlain by a copper-rich primary sulphide zone.

Adi Nefas
The Adi Nefas deposit occurs as an elongated north-northeast trending steeply east dipping massive sulphide layer that is hosted within an upright bimodal sequence of metavolcanic and derived metasedimentary rocks. The massive sulphide unit ranges in thickness from 5 m to 20 m and is largely hosted within a hydrothermally altered felsic quartz-sericite-chlorite-pyrite schist which in turn is flanked above and below by altered metabasaltic rocks. The altered felsic sequence ranges in thickness from 25 m to 60 m.

The Adi Nefas gossan comprises a silica, hematite and goethite-rich assemblage and averages some 10 m in width, and is mapped along strike for almost 2 km.

An upper oxide zone and underlying transition zone are leached and particularly depleted in copper and zinc relative to the primary sulphide mineralization. A slight enrichment in gold is reported for these zones. The base metal tenor increases slightly with depth in these zones. These zones typically extend to groundwater level at a depth of 20 m to 30 m. At and below the groundwater level, the supergene zone contains significantly enriched copper and gold and slightly enriched silver relative to the primary sulphide mineralization. Zinc is still depleted relative to the primary zone. The supergene zone is typically 20 m to 40 m thick.

Gupo
Locally, the highest grade gold mineralization occurs in crystallised, coarse-grained pyrite within quartz veins as well as lower grade gold mineralization in medium to coarse grained, euhedral to sub-euhedral pyrite within a sericite alteration halo. This alteration halo varies in width from few centimetres up to several metres depending of the thickness of the quartz veins, width of the shear zone and the porosity of the host rocks. The quartz veins form a complicated network of stockworks that pinch and swell, within the shear zone.

The Gupo gold deposit has been defined at surface and drilling over about a 1.6 km strike length and a 10 m to 20 m width. These zones are divided into two zones; Gupo North and Gupo South separated by a 400 m long barren zone which is interpreted as a late stage normal fault zone associated with the uplifting of these terrains of the Arabian-Nubian Shield during the opening of the Red Sea.

The Gupo North zone splits into eastern and western sub-zone half way to the south, probably representing the root system of the gold mineralization uplifted by the normal fault.

Debarwa
Three distinct vertical zones of mineralization are recognised at Debarwa. A surface oxide gold zone from which base metals have been predominantly leached, extends to approximately 80 m depth from the highest points and is underlain by an enriched copper supergene zone to around 110 m depth. The supergene zone is in turn underlain by a copper-rich primary sulphide zone which is between 5 to 20 m thick. A thin precious metals-enriched transition zone the oxide from the supergene zone. In addition, remobilised copper mineralization forms a halo surrounding the supergene zone. The geological interpretation identifies the following:
• Gossan (oxide zone).
• Transition zone.
• Supergene zone.
• Primary zone.

Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

Personnel

Job Title	Name	Profile	Ref. Date
.......................	.......................		Dec 13, 2024
.......................	.......................		Dec 13, 2024