Shandong Gold Mining (Hong Kong) Co., Limited ("SDG Hong Kong"), an overseas wholly-owned subsidiary of Shandong Gold Mining Co., Ltd., and Cardinal Resources Limited ("Cardinal Resources") entered into the Offer Implementation Agreement on 18 June 2020. SDG Hong Kong completed the acquisition in March 2021 in accordance with the 2001 Companies Act of the Commonwealth of Australia of 100% shares of Cardinal Resources, which became a wholly-owned subsidiary of SDG Hong Kong accordingly.
Cardinal Namdini Mining Limited ("Namdini") is a wholly-owned subsidiary of Cardinal Resources.
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Summary:
The Namdini has many characteristics typical of mesothermal Birimian gold deposits.
The Namdini gold deposit is a large, structurally controlled, orogenic gold deposit within the Nangodi Greenstone Belt, with numerous features similar to deposits found elsewhere in late Proterozoic Birimian terranes of West Africa. To date the Namdini gold deposit has been delineated over a strike length of 1.15 km, up to 300 m wide and 700 m deep.
The rock types comprising the Namdini Gold Project included a steeply west dipping Birimian sequence of interbedded, foliated, metasedimentary and metavolcanic units which have been intruded by a medium-grained granitoid and diorite. The southern part of the Project is covered by flat-lying Voltaian Basin clastic sedimentary rocks that have been deposited unconformably on the Birimian sequence and postdate mineralization and the host sequence.
Underneath the weathering profile, the Birimian units include metasedimentary, metavolcanic, granitoid (tonalite) and diorite. The metasedimentary and volcaniclastic lithologies have been intensely altered with a resulting pyrite-carbonate-muscovite-chlorite-quartz assemblage. Alteration is most prevalent in the volcaniclastic units. Similarly, the tonalite is extensively altered and has been overprinted by silica-sericitecarbonate assemblages.
In all rock types, the mineralization is accompanied by visible disseminated sulfides of pyrite and very minor arsenopyrite in both the veins and wall rocks. In diamond drill core, the mineralized zones are visually distinctive due to the presence of millimetre to centimetre wide quartz carbonate veins that are commonly folded and possess yellow-brown sericite-carbonate selvages. Rare visible gold occurs in strongly altered granite and is associated with sub-millimetre wide silica-sericite shears.
Typical shallow weathered zone:
- Average base of strong oxidation: 7m;
- Average depth to fresh bedrock: 15m.
Gold mineralisation:
- Localised in the 300-400m wide Namdini mineralised “corridor”;
- Dominantly hosted by the three main lithologies located within it: Metavolcanics, granitoid and diorite.
Gold at Namdini is dominated by electrum (80% of measured grains) with the remainder as native gold.
Gold grains are generally fine; QEMScan analysis indicates 89% <10 microns.
Visible gold is rare and usually occurs as a vein selvage with chlorite in late-stage remobilised veins.
Gold dominantly occurs as inclusions and fractures in;
- Pyrite (75%);
- Arsenopyrite (8%);
- Quartz and other silicates (6%);
- Chalcopyrite (2.5%).
Circa 5% of gold grains are free gold.
Sulphides in decreasing order of abundance are:
- Pyrite, arsenopyrite, chalcopyrite, galena;
- Trace sphalerite, molybdenite, pyrrhotite, gersdorffite and tennantite;
- Rutile, ilmenite and magnetite are alsob associated with gold mineralised zones;
- Pyrite mostly exhibits grain sizes in the 20 to 140 micron range.
Drilling has outlined mineralization with three-dimensional continuity, with a size of approximately 1,500 m long, 550 m wide, and 450 m in depth.
The primary rock is a muscovite rich phyllite that shows extensive carbonate replacement. The phyllite hosts a major sulfide content and significant gold. The fine-grained muscovite shows a moderate preferred orientation and is heavily impregnated with ankerite carbonate.
The dominant ore minerals are pyrite and arsenopyrite that occur relatively commonly through much of the phyllite matrix. Tennantite, chalcopyrite, pyrrhotite, galena, and sphalerite all occur as fines within some pyrites. Magnetite was also detected once.
About 25 occurrences of gold were detected optically. The vast majority occur as inclusions in pyrite. The gold appeared low in silver. These included golds in pyrites that were predominantly under 5 µm, with the exceptions of a linear nature, reaching 25 µm. Most were single particles plus a rare trio.
The host pyrites had a wide range of grainsizes from 50 to 600 µm. Two occurrences of gold were single, fine grains of 2 µm within silicate.