Herberton Tin Project

The project is located 70km south west of Cairns in Far North Queensland and incorporates the regional towns of Herberton, Irvinebank and Watsonville. Infrastructure in the immediate area is excellent with respect to sealed road access, power, workforce, suppliers and proximity to port (sealed road access to Cairns and Townsville).

The project comprises four granted exploration permits (mineral) (EPM) with a combined total area of 534.6km² as well as 11 granted Mining Leases (ML) and 9 Mining Lease Applications (MLA).

 

Figure 1: Tenement Locations

 

The Project is located within the Hodgkinson Province and is bounded to the west by Precambrian aged schist, amphibolites and gneissic granite. These rocks are faulted against the Mid-Silurian – Lower Carboniferous sedimentary units of the Hodgkinson Formation which is a thick clastic marine sequence of greywacke, sandstone, shale, slate, minor basic volcanics and chert. This sequence is intruded by and overlain by Palaeozoic igneous rocks which are interpreted to be associated with mineralisation in the area.

Tin mineralisation is widespread throughout the region occurring mainly as cassiterite within greisen zones to certain granitic bodies, skarn rocks and younger intrusions such as the porphyry sill at Baal Gammon. Economic tin grades are mainly associated with altered and structurally deformed zones occurring as veins, lodes and pipe-like structures. Weathering and oxidisation is relatively shallow in the Herberton area (10-30m), particularly where primary cassiterite and base metal sulphides occur.

Monto are primarily targeting relatively high grade tin oxide cassiterite mineralisation which has been historically simple to process from a metallurgical perspective as it is devoid of the inherent complexities often associated with polymetallic skarn-hosted tin mineralisation.

Since discovery in 1880, significant quantities of tin, copper and silver have been produced from the Herberton region. Historically there has been in excess of 150,000t of concentrates mined from the field, including approximately 109,000t of tin concentrates (concentrate comprising ~70% Sn – 76,300t of tin metal).

The EPMs host over 2,000 former mining operations, from small alluvial workings to relatively large open pit and underground operations such as the Vulcan Tin Mine which was mined to a depth of 425m with a grade over 6% Sn for almost 14,000t of tin concentrate.

The Arbouin Tin Mine was also a significant high-grade producer which ceased operations in 1987, with underground drilling in unmined areas returning intercepts of 26.4m @ 2.78% Sn. The Arbouin Tin Mine, along with many of the historical mines in the project area, represent walk-up drill targets for the identification of both lateral and vertical extensions of the known mineralisation, associated potential lower grade haloes and nearby repeat structures and/or independent structures hosting mineralisation.

The Herberton Tin Field has historically been comprised of extremely small plots pegged by local prospectors, leading to a patchwork of licences with no centralised focus with respect to mineral exploration. In 2006 the smaller plots were successfully acquired and consolidated into the existing relatively large EPMs by former ASX-listed company North Queensland Metals (NQM). Conquest Mining completed a takeover of NQM in November 2010. Until the licence consolidation was achieved there had been no coordinated regional approach to exploration in the area and no utilisation of modern exploration techniques. This in itself has presented a genuine opportunity for Monto to apply modern exploration methods to a highly prospective metalliferous province that has been underexplored as a function of the previous land tenure situation.

Following consolidation of tenure, NQM instigated an airborne magnetic survey over the tenement package. This was the first survey of its kind covering the area and has facilitated a regional assessment of prospects and mineral occurrences. Areas of further interest were followed up with ground-based magnetics and induced polarization (IP) surveys.

NQM have also completed a series of significant rock-chip, soil sampling and drilling programmes in the area which have generated some attractive anomalies requiring follow-up work. Monto is in receipt of the extensive NQM Herberton electronic database.

Detailed target generation exercises based on geophysical surveys and soil, rock chip and drilling programmes have been conducted by NQM, identifying over 14 compelling tin targets. Of these, the following areas have been identified as potentially containing high tonnage deposits with viable grades:

• Herberton Hill
• Elaine-Boundary
• Arbouin-Peacemaker-Pompeii
• Sailor

The Sailor prospect is located to the south of the main group of EPMs and is located within 10km of Consolidated Tin's (ASX: CSD) Windermere Deposit that comprises the Mt Garnet Tin Project. The Mount Garnet Project has a total JORC Code-compliant resource of 7.3Mt @ 0.6% Sn.

 

Figure 2: Aeromagnetic Image Showing Herberton Tin Targets

 

The region is also highly prospective for lead, zinc, silver and gold. A number of targets have been identified for each of these metals, including Zig Zag, Elizabeth Bluffs, Orient and Lancelot/Magnum Bonum, again centred on historic workings.