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Title: | Annual report on MCN's 2631 and 723 Mount Wells Northern Territory June 2006 to Jan 2007 |
Title Holder / Company: | Softwood Plantations |
Report id: | CR2007-0651 |
Tenure: | MCN2631; MCN723 |
Year: | 2007 |
Author: | Morrison, J |
Abstract: | Mt Wells site to promote mining in the Pine Creek area. Other buildings including accommodation and tailings dams were also constructed around this time. Jingellic Minerals became interested in the Mt Wells site in the 1970's, opening the east lode underground workings. Further drilling was carried out by and the Northern Territory Mines Dept, between 1971 and 1977. Approximately 100t of ore was removed in 1978 by Millwood and Murray. Alluvial mining was carried out between 1978 and 1980 by Territory Mining. They excavated approximately 300, 000m of regolith from the watercourse between bottom dam and the McKinley River. In 1980 Jingellic Minerals upgraded the government battery and replaced the gravity stamp with a rod mill. The mill processed ore until 1983 when the mill was closed, but was reopened to process ore between 1985 and 1986. Territory Resources then acquired the tenements and commenced a prefeasibility report. A drilling program was developed to assess mining the West Lode as an open cut prospect. In 1989 RC drilling by Territory Resources commenced. Territory Resources carried out substantial deep drilling, analysis, and sampling and extended the drive and tramway to the east lode. The records for 20 of the drill holes are available, as well as the assay results. Cross sections of the drill holes and maps of the site are also available. In 1994 Territory resources sold the Mt Wells site to Softwood Plantations. Previous exploration on Mt Wells area has estimated a possible underground estimate of 737 000 t of ore averaging 1.38 % Sn, and a further open cut estimate of 400 000t of ore grading 0.4%Sn. Furthermore an estimate of 971 000 t of ore grading 1.5% Cu plus wolfram credits has been located at the Mt Wells site At present a plan exists to open cut the combined Copper/Tin/ Wolfram resources at Mt Wells. Softwood Plantations Pty Ltd proposed to commence open cut mining tin from the West Lode and Main/Intermediate lodes located at Mt Wells. Previous drill programs at this site focussed on the potential of deeper ore which would be accessed by underground methods. Softwood carried out a drilling and sampling program to target shallower ore. Several areas of high grade tin ore were discovered during the surface sampling. Following assays of the drill and rock chip sampling, a plan was developed for the surface of the Mt Wells tenements and all data compiled from Territory and Softwood and then plotted using computer modelling techniques. At this time period the price of tin fell from $2.4426 USD / Lb to $1.6783 USD/Lb. It was deemed uneconomical to continue to explore and mine at this time. The increase in tin prices over the last year has warranted the renewal of detailed feasibility studies to commence. As part of the desktop studies completed by Softwood Plantations a review was made of the resources estimates in 2000. This review was relevant to determine the accuracy of previous estimates as the accuracy of information will affect the mining widths, which will be a factor of the current metal prices and mining processes. There were sufficient assays of vein material to say that in the main lode systems (West, Main and East), the average quartz grade is 1.5-2% Sn, and in the tourmaline/quartz greisens 1%. The metal prices will affect the actual mining process as the as the ore grade zones 1 and 2 are separated by below cut-off grade material that will cause dilution. High metal prices will mean a bigger bucket on the excavator with less detail taking out the quartz vein, and the inclusion of more of the lower grade tourmaline breccias. This will naturally mean more tonnes of ore and will affect the ore to waste ratio. A study of the historical mining indicated that the mineralisation is hosted by strongly sheared siltstone containing veinlets of Sn, Cu and As. The mineralisation suddenly widened where the vein extended into massive greywacke, which hosts the main lode proper workings, which hosts the bulk of the ore material. The vein then re-enters the siltstone 100m north of the main open cut at a distance of 300m. Due to a collapse in 1912 of the open cut, which filled the upper levels of the mine with low grade ore from the footwall of the open cut, it is not possible to observe the southern limit of the vein. Surface prospecting has revealed the main vein with a width of up to 0.6m containing abundant coarse cassiterite. Because of the steep slope some of the veins in the area were never explored. Similar material crops out, unworked, at the NW Lode and the No. 4 lode. Based on observations, sampling, RC drilling and chip sampling of old working a length of 250m, with a width of 6m of ore there is a tin reserve figure of 506,250t. The west lode is in fact only in its initial stages of exploration. Mookhey perhaps made an over sight and misinterpreted the Mt Wells history. Mookhey has mis-quoted Smith from BHP, in defining the ore production and saying the grade was only 0.22% when in fact is was defined as off limits by the lease holders who wished to retain that area to mine themselves. Smith quotes a recovered grade of 4%. These workings are partially accessible to a depth of 25m. There is very little surface work in this area, although a vein was followed down to 60m with an unknown amount of ore produced. The block has been drilled between 10 200N to 10 250N (DDH5) and produced ore grade Sn and Cu results at depth. It is suggested that drill hole W1 between 10200N and 10250N to a depth of 65 m has reserves in the order of 55 000 and W2 shows the ore grade extends to 167m below the drill collar. (Approximately 50 m above the adit 3 as calculated by T Bates) To the south of the RC holes 4, 5, and 6, a bulldozed cut exposes 1.5m of quartz. Rock chip sampling indicates a narrow 1-2m mineralised zone falls within this cut. Using these figures (125m by 1.5m by 125m) it could indicate another speculative 50,625 t of ore grade material down to level 3 adit. West Lode No.2 This lode is recognised from pot holes and costeans on the surface. There is cassiterite bearing quartz tourmaline cropping out over about 150m with drill intercepts in RC 20 and DDH 4 and 5. This lode appears to be approximately 2m wide and occurs about 90m above adit 3 level. With a strike of 150m and a depth of 90m and a width of 2m we can speculate approximately 72 900t of ore grade material. No.1 Copper Lode This is known from the stope in adit 3 driver on for about 15m average mine samples were 0.73%Sn and 0.42%Cu%. Average channel samples in northern part of the drive produced 0.58%Sn and 0.98%Cu, while the southern oxidised part of the drive 1.0% Sn. Chalcocite bombs are scattered through the kaolinised fault zone. A sampled bomb from this area assayed 63.5% Cu. The lode has been encountered in DDH4 (1.5%W) and DDH7 with 0.03% Sn and 1.37%Cu. At the surface it is exposed intermittently amongst heavy scree as a quartz vein 40cm wide and strongly mineralised with cassiterite and wolframite. Bates mapped a small stope in Adit 2 where it contains coarse cassiterite. The approximate strike length is 100m with a width of 2m and the surface to adit 3 level is 55m down dip. This gives an approximate 29,700t of ore grade material. No 2 Copper Lode The No.2 copper lode is known from exposure in Adit 3, Adit 2, on surface exposure in pits and open cuts on both the north and south side of Mt Wells. It can also be traced in most of the DDH holes. The dominance varies from Sn, Cu, and W depending on where the sample is from. It is underexplored and its true extent is unknown. It is a persistent feature and probably has a strike of 250m, a width of 3m, and an average outcrop to adit distance of 90m down dip. This indicates a possible 182 250t of ore grade material. The East Lode This lode crops out over a distance of 330m of which 275m has minable grades. The lode has extensive surface workings and is mostly worked out at its southern end. This area would be within the final pit out line some 10 000t of low grade ore would remain. IMC Development Company drove test shafts north from the intersection of Adit 3 and the East lode and assays done and described in Mookhey (1971) produced sub economic grades of Sn, Cu and W at the intersection of the lode and Adit3. If the footwall veins and other parallel veins are included in the grade it drops from 1.6%Sn over 1.2m to 0.8% Sn over 3m It is however easier to maintain 0.8 % grade over 3 m that 1.6% Sn over 1.2m. An approximation of this area is 100m strike with 3m width and 90m depth will give 72 900t of ore grade material. North West Lode Crops out strongly as a quartz gossan and haematite gossan vein over a length of 100m. The southern gossan zone was drilled (RC9 and 10) and intercepted a fairly good alteration zone it was poorly mineralised and failed to achieve ore grade. As with all coarse cassiterite, it can tend to form aggregates of mineralisation with a spotty nature. More investigations will need to be done on this lode. No 4 Lode. Very little information about this lode is available it is approximately 50m long and consists of a stockwork of 10 - 30 veins and with a width of 10 - 20 cm. The stock work area is approximately 5 m wide and visible cassiterite and wolfram is contained in this lode. Using these figures an estimate of 33 750t can be speculated. These figures are an indication of what ore may exist between Adit level 3 and the surface. 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. Since this transaction was proposed an audit of the current resource statements has been made as well as the development of an infill drilling program has been proposed. The purpose of this infill drilling program will be to prove up the possible resources to a JORC compliant resource statement and then to develop the Mt Wells site into production. This program will begin in February 2008 using a RC drill. |
Date Added: | 15-Aug-2017 |
Appears in Collections: | Minerals Exploration Reports (MEX) |
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