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Oct 2016 - Mantle Mining Corp

Mantle Mining Corporation Limited (MNM) – Reviving the Woods Point Goldfield

  • Mantle Mining (MNM) has recently acquired most of the Woods Point goldfield in Eastern Victoria, and applied for an EL covering most of the remainder. The project area covers a NW/SE striking dyke swarm in which the dykes have periodically bulged along their length. Within the dykes there are flat, east dipping and west dipping lodes, comprised commonly of visible gold in quartz, and which appear to have been usually enriched mostly on the upper edges where the lodes pass from the bulge into the sediments. 
  • The Morning Star mine is perceived to be the main asset, and it went through two major mining profitability periods, the first being after its discovery where parts of the hill graded up to ~44oz/t, and in 1865 when its expected average grade was 3.1oz/t (~100g/t), with some 266koz mined at ~2oz/t (~70g/t) in the first 9 years to 1869. And the second by GMA (part of WMC) from 1935 to 1963 for ~255koz at 0.65oz/t (~22.4g/t), when it closed due to increasing depth, power-line costs and a low gold price (US$35/oz[A$32/oz]). The last operator (MCO) went into receivership in late 2014, due to ignoring the historical records.
  • Quite surprisingly although historically stated in more than one place (even since the 1860s) that the richer gold grades at Morning Star were in "dyke over sediment" on the contact, ie on the up-dip side, so for an east dipping lode or reef, the higher grades are on the western side. The previous owners (MCO) went into insolvency targeting the down dip sides of a number of reefs, which when developed, found they were uneconomic.
  • Visiting the nearby, operating, A1 Gaffneys gold mine, highlighted a number of reefs that have been encountered, but barely exploited at Morning Star. Such as the breccia zones (currently being mined by A1 at ~10.5g/t [and discovered in an area of older stopes]), or the "mutton-fat" lodes (of which A1 has mined 3) being degenerated quartz near the payable reef, grading 3g/t to 10g/t or higher.
  • However, of greater potential has to be the shape and length of the dyke bulge, A1's has increased from ~200m to >500m long and is completely non-uniform vertically and horizontally as shown in Figures 11 and 12. Morning Star's dyke bulge still has the same profile of its 1902 plan by Whitelaw, with barely explored north, south and lateral extensions or even parallel structures as have been encountered in other dyke bulges.
  • Although there is a dyke swarm, it seems that only the main bulges were focused on, there are bulges that were not continued for one reason or another and have not been looked at for ~90 - 100 years. The Rose of Denmark for example was mostly mined/stoped outside of its dyke bulge over its 62-year life to 1926. The swarm also includes a number of pure auriferous quartz veins that appear to have mostly lain dormant for over 100 years.

Other Key Points

  • Infrastructure is good, as in most of the mine areas do seem to have historical access roads, and some refurbishment was made by MCO, however, the terrain does consist of steeply incised valleys.
  • Vertical mineralisation "gaps" in the bulges appear to be fairly common, and perhaps drilling beyond the possible >100m vertical gap is then required. • Some of Mantle's other gold projects look interesting, such as near Charters Towers, its NW/SE striking vein system at Granites Castle, or Norton project near Gladstone, but they have not been considered in this report.
  • Ranking the numerous Woods Point prospects is required for exploration and may have to include their ability to be mechanised or mined by open-cut.
  • Written by: Keith Goode
  • Wednesday, 26 October 2016