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At Jervois, approximately 290 km north-east of Alice Springs, the discovery of vanadium-bearing magnetite represents further potential to diversify Arafura's commodity base. The project is secured by EL 10215, EL 26231, EL 26318 and
EL 26812.
The Bonya Schist is the dominant outcropping Palaeoproterozoic unit within Arafura's licence areas. It is predominantly composed of pelitic, psammopelitic and calcareous metasedimentary rocks, all metamorphosed at upper greenschist to lower amphibolite facies conditions. The Attutra Metagabbro occurs as a series of low hills on the licences. It is described as altered gabbro, dolerite, norite and magnetite rock. Titanium-vanadium-rich magnetite occurrences, some with anomalous copper-PGE-gold, are known within the Attutra Metagabbro in the north-eastern parts of EL 10215. Past exploration efforts have not fully evaluated the extents of these occurrences.
Encouraging results from systematic programs of surface geological mapping, rock chip geochemical sampling, and airborne geophysics by Arafura in 2005-2006 culminated in a 15-hole RC drilling program in October 2006. Drilling confirmed the sub-surface continuation of several near-massive magnetite horizons up to 44 metres in thickness over an area of approximately 20 km2. The average grade of in-situ (head) material from all mineralised drill intercepts is 29.2% Fe, 0.47% V2O5 and 6.48% TiO2, confirming the tenor of earlier surface rock chip assays.
Recovery of magnetite concentrate using an industry-standard process shown below (Davis Tube Recovery - DTR) delivers an average physical yield of 27.9% grading 64.5% Fe, 1.34% V2O5 and 5.22% TiO2. Metal recovery in concentrate averages 61.5% for Fe, 76.4% for V2O5 and 22.2% for TiO2.
Based on these results, the Jervois Project has the potential to provide good vanadium yields to a clean concentrate.
A second-phase drill program, comprising 45 RC holes for 4,840 metres, was completed in the first half of 2008 to better outline the extent of mineralisation intersected in 2006, and to test new target areas. Interim assay and recovery results from this program at Jervois were reported in July 2010. Arafura recommenced the assay process following its suspension in late-2008 due to financial constraints, and subsequent unsuccessful JV negotiations with the East China Mineral Exploration and Development Bureau.
Reporting of results is thus far confined to the Casper prospect in the south-eastern part of EL 10215, which produced some of the more significant vanadium-bearing magnetite drill intercepts in 2006. The length-weighted average results for all mineralised samples from drilling of the Casper prospect in 2008 is as follows:
Metres of mineralised drill intervals used in weighted average |
RC Drill sample assays
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DTR |
Concentrate assays
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Recovery in concentrate
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Fe |
V2O5 |
TiO2 |
Rec |
Fe |
V2O5 |
TiO2 |
Fe recovery |
V2O5 recovery |
TiO2 recovery |
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668 |
21.7 |
0.48 |
4.76 |
19.1 |
64.3 |
1.69 |
4.65 |
54.3 |
66.0 |
18.2 |
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Further assay and recovery results are expected during the latter part of 2010.
