Strandline Resources (ASX:STA) has identified new high grade heavy mineral sands targets in Tanzania from a mapping and sampling program conducted in late 2014.
Two of the priority locations are located on Mafia Island in central Tanzania and another at the Kiswere Project in southern Tanzania.
The important characterisation and assemblage tests were completed to firstly quantify the percentage of total heavy minerals (THM) in the surface samples and then to establish the percentage of valuable heavy mineral (VHM) which excludes any trash (non-valuable) component of the THM.
Separately, auger drilling at the Ziwani Project has defined 2.85km long anomaly 8 kilometres along strike from the high grade Madimba East mineralised zone.
“Our first stage sampling programs are proving to be exceptionally encouraging,” managing director Richard Hill said.
“With some surface sampling results testing over 80% THM and with excellent VHM contents ranging from 59% to 80%, we are very keen to drill these new high priority drill targets as soon as possible in 2015.”
The mineral assemblage and mineral chemistry data presented by the company are the first known detailed analyses for HMS mineralisation on Mafia Island.
For the Mafia Island samples, VHM ranges from 59% to 80%, with an average of 72% VHM.
Ilmenite is the most abundant titanium-mineral, and combined ilmenite+altered ilmenite in VHM varies from 51.3% to 69.7%. Rutile varies from 1.81% to 2.35%.
Average grainsize for ilmenite and altered ilmenite, in the >45μm to -1mm fraction that was analysed is quite coarse in size ranging from 94μm to 135μm.
For rutile and zircon in the same size fraction, grainsize averages from 80μm to 107μm, and 77μm to 98μm, respectively.
Altered ilmenite is a high-titanium mineral species with between 55 and 70% TiO2.
The TiO2 deportment is generally dominated by ilmenite, although in ACT006 it is split roughly 50/50 to ilmenite and high titanium altered ilmenite. In terms of TiO2 within Ti-oxide minerals, the ilmenite fraction typically contains 44.6% to 44.7%, and altered ilmenite contains 51.5% to 54.3%.
Importantly, the ilmenite and altered ilmenite contain low contaminants such as chrome and alkalis which have an impact on the potential processing routes, and therefore, value of the raw product.
Evidence of modern accumulations of high grade mineralisation was identified at a number of coastal locations within the Mafia Island tenement.
The significance of the high tide concentrations on the current beaches are evidence that firstly, there is a significant source of heavy mineral eroding from the mixed sediments forming topographic highs on the island, and secondly, modern shore line processes are concentrating the heavy mineral as strandlines.
Given these observations, it is possible to interpret that older paleo-strandlines could have developed in the low-lying coastal plain environment as the shoreline has migrated seaward.
The Kiswere sample returned a VHM assemblage of 85% after normalisation for the quartz dilution.
Ilmenite comprises 62.8% of VHM while average ilmenite TiO2 from this one sample is 47.3% which is within typical 45%-58% TiO2 parameter for sulphatable ilmenite.
In terms of deleterious elements the ilmenite and altered ilmenite contain low contaminants such as chrome and alkalis. Average grainsize of the ilmenite in the >45μm to-1mm fraction, is 100μm.
Zircon comprises 9.54% of the THM after normalisation and has an average grainsize of 92μm in the >45μm to-1mm fraction. Rutile content is 1.8% in the normalised THM data.
It should also be noted that the Kiswere sample was not a concentrate sample, but a standard surface channel sample.
Thus the 3.45% THM grade for that sample when combined with mineralogy and chemistry data is an important exploration outcome for the Company as the sample site coincides with an interpreted paleo-marine terrace and may represent mineralisation associated with a palaeo-strand.
Historic sampling at Kiswere is very sparse and the company has 30 kilometres of strike along the current and paleo-coastlines, representing a significant target area warranting further investigation.
This will involve reconnaissance auger drilling the interpreted paleo-marine terrace focusing around the mineralisation discovered by the company.
Ziwani Auger Results
The shallow, wide spaced auger drill program of 25 holes at the Ziwani tenement has defined 2.85km long anomaly.
The program was an extension of the auger drilling that was completed at Madimba and Madimba East prospects, located directly to the south of Ziwani that encountered high grade THM results.
Results from Madimba include:
- 7 metres at 7.06% THM from surface ending in 12.36% THM;
- 7.5 metres at 4.10% THM from surface ending in 4.8% THM; and
- 6 metres at 3.42% THM from surface ending in 3.31% THM.
The Ziwani mineralised zone is thought to reflect an ancient shoreline and requires further drilling to prove depth extent and grade potential.
Additional samples will be sent for mineral assemblage and characterisation testwork. There may be some synergies between the high grade discovery at Madimba East and larger bulk tonnage potential anomalies at Ziwani and Madimba.
The targets present Strandline Resources with an exploration pipeline to find further heavy mineral sands deposits.
This potential is clearly demonstrated by the company’s desire to drill the high priority targets as soon as possible this year.
Sampling has also indicated low levels of contaminants, which reduces potential impact on processing routes.
Adding to the potential, non-executive chairman Mike Folwell is a former managing director of A$3.3 billion market cap Iluka Resources (ASX:ILU).
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