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The Potential for Rare Metal and Gemstone Mineralisation in the Aïr Mountains, Republic of Niger
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by Wolfgang Hampel (2000), 26 pages, 7 figures, 6 tables and 2 annexes
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Client: GeoAfrica Gold Corporation, Sydney
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Position held: Consultant Geologist
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An evaluation of the
geological potential for economically exploitable deposits of speciality metals (Ta/Nb, Sn, REE, Li, Cs, Rb, etc.) and coloured gemstones in the 70,000 sqkm Aïr Mountains, Niger. Further to that, a two-month exploration program and a detailed budget were to be proposed.
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+ compilation of all available data
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+ description and classification of targets
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+ detailed description and interpretation of the geology
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+ detailed methodology of sampling and assaying
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+ description of known mineralisation
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+ proposition of laboratory and local staff
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+ development of metallogenetic models
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+ proposition of detailed work program
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+ economic considerations
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+ proposition of a US $ 100,000 budget (all incl.)
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Geological setting: The Aïr Massif is part of the Touareg Shield
and the Panafrican Mobile Belt. Major deformations occurred during the Cryogenian (750-660 Ma) and Vendian (650-550 Ma). The crystalline, strongly metamorphosed Suggarian basement was intruded by subduction-related Pan-African granitic rocks (Older Granites). To the west it is separated from the surrounding slightly metamorphosed series by the major Tafadek overthrust, and to the east by the Aouezegeur overthrust. Palaeozoic
alkaline ring complexes
(photo) intruded into the basement and are amongst the largest in the world ('Younger Granites Province' of West Africa). Tertiary to recent volcanics are widespread in the SE of the Air Massif.
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Potential for rare metals:
- eluvial tin is mined since 100y with minor W, Ta/Nb
Excellent potential for:
- stockwork/greisen with Sn-Li-W
- pegmatites with Sn-Ta/Nb-Li-Cs-Rb-REE-Sc, Be, etc.
- hyperalk. syenites with Nb-Zr-Be
- Veins/lodes with Sn-W-base metals
- Rapakivi granites with Sn-Be-W-base metals
- Secondary deposits with Ta/Nb, Sn, REE, W, Sc, etc.
Potential for coloured gemstones:
- to-date only gem-quality topaz (photo) and beryl are known
Excellent potential for:
- pegmatite-related gems (rubies, emerald, sapphire, garnet, etc.)
- skarn-related gems (rubies, etc.)
- schist-hosted gems (zoisite, emerald)
- volcanics with opal and sapphire
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Please note:
The Aïr Massif offers also an excellent potential for base/ ferrous metals
(Cu, Ti, etc.) + lamproite-hosted diamonds. These commodities were not covered in the report but are known from the Aïr and/or the Hoggar/Algeria.
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