Mineral lease bridging reports for MLN's 661-671 inclusive and MLN 680 Maranboy Northern Territory for the period 1964 2006

Abstract

The Maranboy Tin Field is a small inlier of Proterozoic rocks that are surrounded by Cambrian and Cretaceous sediments. This inlier contains mineralised sediments with the main ore mineral as cassiterite. The ore has formed as fine grained cassiterite in quartz and tourmaline fissure lodes infilling systems of conjugate fractures and shear zones. These lodes strike 110 degrees to 160 degrees. The area has been historically mined for tin since 1915. The mineral leases described are located approximately 60 kilometres south east of the township of Katherine, on the edge of the Daly River Basin in the Northern Territory. The Mineral leases cover the areas over the Maranboy Tin Field at latitude 14 degrees 32' South and longitude 132 degrees 47' East. Tin was reported at Maranboy in 1901 and by 1915, 50 prospectors were located at Maranboy. By 1916 a government battery was located at this site and operated until 1952. This battery has subsequently been torn down. Minerals Resources Australia Pty. Ltd. acquired an area which covered the Maranboy Tin field in 1963. They also negotiated options over mineral leases which covered the most productive zones of the main vein. The property was assessed on their behalf by Hare and Associates in 1963. Previously the Bureau of Mineral Resources (BMR) drilled 11 holes over the area with promising results. This drilling established that the main vein below Anaconda extends at depth. Using the information provided through BMR, Minerals Resources Australia determined that mining of the Main Vein Lode would be economically viable and proposed an exploration program in 1964 which included diamond drill holes to test for lodes at depth. The location of these 2 drill holes is unknown. United Uranium assessed the property in 1969 for secondary accumulations downstream from the Stannum King and Main Lodes. The results concluded that the potential was poor and no further work was pursued. Jingellic Minerals NL assessed the tin field in 1973. This report recommended diamond and percussion drilling with limited underground development. Carpentaria Exploration Company (CEC) negotiated with the estate of the late H. Brennan, with an option to purchase 16 leases at Maranboy. In 1980 drilling was undertaken by CEC. Initially CEC incorporated earlier drilling by BMR who drilled 11 diamond drill holes between 1958-59, including 8 holes on Anaconda lease & 3 on Osman lease. The best result was of 1.6m @ 2.05% Sn at 180m. CEC also notes that 2 diamond holes were drilled by Metals Exploration (1964-65), one of which did not intersect ore. The best results for these drills were for 0.4m @ 0.22%Sn BMR drilled 4 more holes at Ray lease in 1971. Carpentaria drilled 5 diamond holes in 1980 with the best results of 0.2m @ 5.6% Sn (Mar3) and 1.18m @ 1.36% Sn (Mar 4). Further percussion drilling by Carpentaria was designed to test for nearsurface extensions of outcropping lode and for deeper extensions of the Lode below depth of previous mining. Both short angled holes and deeper vertical percussion holes were drilled. All of the holes except MAR9 intersected quartz-tourmaline lode material. Three holes intersected grades greater than 1%Sn. Best result of 30m @ 3.06%Sn in MAR11 (Osman lease). The drilling program was followed up with surveying and geophysics over mineral leases. Ground magnetic and radiometric surveys were carried out to determine if the ore bodies could be delineated using these techniques. No correlation was found with the magnetic survey as it was extremely noisy due to cultural features (iron bits in old mines etc). The greisenous zones could be depicted using the radiometric survey. This was useful as the mineralisation was often associated with the greisenous zones, however it was determined that no consistent correlation between geophysics and mineralisation could be found. Ongoing exploration by Carpentaria tested the Stannum King, Main Lode and Ray lease at Maranboy tin fields. Drilling defined the extent of mineralisation to the NW of the Main Lode, and identified ore grade shoots at Stannum King Mine and Main Lode on Ray Lease. It was in November 1982 that Carpentaria determined to sell its interests in Maranboy and suspend any exploration. The Mineral leases were then bought by Territory Resources which was in turn bought by Denehurst Limited. No information could be located in relation to work carried out by Territory Resources. In 1988-1990 surface exploration by Denehurst was carried out on MLN 671 and 680 in conjunction with EL's 2087 and 2148, which surround the mineral leases. Rock chip sampling was used to define drilling targets. The drilling targets were located on EL 2087 and MLN 679, and established that the lodes continued at depth although the grades were low. No drilling records from previous title holders could be located for Mineral Leases 671 and MLN 680. MLN 671 covers the southern strike extension of the Stannum King Lode. The Company planned to explore MLN 671 using various methods such as ground surveying, surface mapping/sampling, drilling, pitting, and geophysics, as part of a regional exploration programme to evaluate the tin resources. The rest of the exploration program was carried out on the exploration licences surrounding the Mineral Leases. In 1991 Denehurst concluded that there was not an economic resource located at this site and decided to allow the licences to expire. In 1997 Softwood Plantations enquired into the purchase of these Mineral Leases, and surrounding exploration licences. Softwood Plantations Pty Ltd purchased Mineral Leases 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, and 671 along with some other Mineral leases on the 1st of October, 1997. Softwood Plantations Pty Ltd purchased Mineral Leases 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, and 671 along with some other Mineral leases in the area on the 1st of October, 1997. Work on the Maranboy tenements comprised of site visits with various geologists, including the Managing Director of Malaysian Smelting Corporation and his chief geologist. Base plans were marked up with reference to the exploration results, showing the location of miscellaneous surface sampling. A prefeasibility model was set up and several prefeasibility models were run over several years. During this time period the price of tin fell from $2.4426 USD / Lb to $1.6783 USD/Lb. These models were adjusted to compensate for the fluctuating tin price and discussions that were held with various mining contractors. These discussions reviewed the various costs and mining options involved with developing a surface or open cut mine, and the relevant costs of processing and mining. Several trips were made to Malaysia and China and various meetings held with financiers regarding the provision of development finance for the mine. At the end of 2006 the price of tin had risen to $5.3978 / Lb and a program to re-establish the possible resources and develop the resource was undertaken. Attempts were also made to source used plant equipment for the mine and new technologies investigated. Mapping, sampling and drilling had been previously carried out to establish a possible resource of 172 000 tonnes at 2.18% tin, and additional 550 000 tonnes at 2% tin was also estimated. During 2007 a proposal was made by 'Outback Metals Ltd' to acquire 'Softwood Plantations Pty Ltd'. In anticipation of this transaction being completed a decision was made to suspend all exploration activities. The Maranboy Inlier is essentially an anticline of folded lower Proterozoic sediments of the Burrell Creek Formation. This anticline plunges to the south east at 30o and exhibits crenulations. The mineralization is associated with cross cutting faults that strike mostly east north east with the Main and Stannum King lodes occurring on the northerly side of this anticline. The fault trend is for offset continuations of tin bearing, tourmalinised greywacke and the brecciated greywacke that forms a cherty white groundmass. These faults can be up to 2 m wide with some minor adjacent faulting striking to the east or the south. The lodes are identified by their very dark and dense outcrops of tourmalinised greywacke. They are usually tabular and can be as wide as 2 m and continue for over 1000m along strike. They dip steeply to the north east and the ore occurs as cassiterite. The associated gangue minerals are tourmaline, quartz, hematite with minor chlorite and talc. The ore is bound up during tourmalinisation of the greywacke, and forms euhedral crystals occurring with tourmaline and quartz in veinlets, in miniature stock work features and as vugs within the veins. The cassiterite formation is spotty and due to the fine grained nature of the cassiterite mineralisation it was determined, through tests carried out by the CSIRO in conjunction with Melbourne University, that to maximise the amount of tin recovered through processing the ore needs to be ground down to quite a fine ore.