- Mafia Island Project - Very high grade results from 3 separate locations at Mafia Island returned:
* 81.1%, 26.3% and 7.48% Total Heavy Mineral (THM)
* Excellent (range 59% to 80%) Valuable Heavy Mineral (VHM) content of the THM
* Including high grade zircon (up to 17.9%) and high portion of high titanium content "altered Ilmenite" within the VHM
* Low contaminants.
- Kiswere Project - Surface sample associated with potential strandline feature with up to 30km of potential strike returned up to 3.45% THM with good mineralogy and low contaminants.
- Ziwani Project - Auger drilling defines a 2.85km long HMS anomaly 8 km along strike from the high grade Madimba East mineralised zone.
- Newly discovered prospects represent high priority drill targets.
Late in 2014 the Company completed a two week mapping and sampling programme across a number of priority target areas in its extensive 2,000km2 Tanzanian mineral sands portfolio. Two of the priority locations included Mafia Island (central Tanzania) and the Kiswere Project (southern Tanzania). From that initial survey, a total of 4 surface samples, 3 from Mafia Island and 1 from Kiswere, were submitted for THM grade, mineral characterisation and assemblage tests.
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.
THM and VHM results are presented in Tables 1 and 2 in link below.
Strandline Resources Managing Director, Richard Hill said, "our first stage sampling programmes are proving to be exceptionally encouraging."
"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 Mafia Island samples were gathered from current beach environments, while at Kiswere the sample was taken from a locality where heavy mineral sand was observed to be liberating from loosely consolidated soils.
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% (ACT006) to 80% (ACT004), with an average of 72% VHM, an excellent result. 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.
Sample ACT003 contains a very high proportion of zircon in the VHM, at 17.9%.
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 (see Figure 1 in link below). 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.
Figure 1 (in link below), inset A shows an example of a modern heavy mineral accumulation at the high water mark on the southern coast of the island. The heavy mineral strandline extends for 700m along the shoreline. Figure 1, inset B is a photograph taken from another location on the western side of the island. The image shows very high grade heavy mineral mineralisation at surface and at the bottom of the hole. Mineralisation was identified along a 2km stretch of beach at three locations.
It is anticipated that any older strandlines discovered by the Company will have similar ratios and percentages of the valuable heavy mineral species. This is a high priority target and exploration to be carried out in the short term will involve auger drilling the coastal plain environments targeting the older palaeo-strands which may contain significant high grade tonnages of HMS.
The Kiswere sample, ACT007, after normalisation* for the quartz dilution returned a VHM assemblage of 85%.
Ilmenite comprises 62.8% of VHM in the normalised data. 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.
The historic sampling at Kiswere is very sparse (see Figure 2.) and the Company has 30km 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.
*Normalisation: normalising involves the removal of dilutionary quartz and other silicates which should not be part of the typical heavy mineral suite. The removal of the silicates has the effect of increasing the VHM content within the THM. Normalising is only undertaken where there is an unusually high component of silicates in the heavy concentrate.
Ziwani Auger Results
Results have been received from the shallow, wide spaced auger drill program that was completed over the Ziwani tenement in Southern Tanzania. The program comprised 25 holes for 135.2 metres with an average depth of 5.4m. The drill spacing was irregular and followed existing tracks approximately 1 to km apart along strike. Holes were drilled on a broad spacing of 400m apart on the lines.
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. As previously reported the Madimba results include the following (refer to the ASX announcement dated 5 February 2015 for further details):
- 7m @ 7.06% THM from surface ending in 12.36% THM
- 7.5m @ 4.10% THM from surface ending in 4.8% THM
- 6m @ 3.42% THM from surface ending in 3.31% THM
The Ziwani anomaly is large at approximately 2.85km long and extends in a northwest orientation located 5km inland from the current shoreline. 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 projects are located only 25km from the port of Mtwara.
To view all figures and tables, please visit:
About Strandline Resources Limited
Strandline Resources is an Australian Stock Exchange listed company (ASX:STA) (OTCMKTS:STQNF) is a Tanzanian-focused mineral sands developer positioned within the world’s major zircon and titanium producing corridor in South East Africa. Strandline has a dominant mineral sands position with a series of 100% owned projects spread along 350km of the Tanzanian coastline.
Strandline’s strategy is to develop and operate quality, low cost, expandable mining assets with market differentiation. Leveraging off the exploration success of 2016, the Company’s focus is to continue its aggressive exploration and development strategy to progress economically attractive projects based on high unit value titanium and zircon products.
Strandline Resources Limited