Mt Garnet Mine History
The Mt Garnet mine was first mined by the Mount Garnet Freehold Copper and Silver Mining Co. Ltd, and was part of the John Moffatt mining ‘empire’ . They commenced mining secondary copper in 1898 and then smelting copper ore in 1901. Copper rich ore was sourced from two main pits, the No. 1 Pit developed on the South Shoot, and the smaller No. 2 Pit developed on the North Shoot as the mine contained two lenses staggered vertically and plunging gently to the north. Underground development extended to around 72.6 metres depth with limited stoping. The oxide and transition ore were exhausted by 1902 and smelting operations ceased. Tribute mining continued in 1904 and, from 1915 to 1917, a trial zinc mining operation was attempted, unsuccessfully.
Zinc Corporation, Metals Exploration and CRA Exploration (CRAE) explored the Mt Garnet area (including diamond drilling) from 1947 to 1974. Reverse Circulation (RC) and diamond drilling were completed by the Mt Garnet Joint Venture partners Perilya Mines N.L., Cove Mining N.L., Foster Allan N.L. and Falcona Exploration and Mining N.L between 1989 and 1991 inclusive.
The project was acquired by Kagara Limited (Kagara) in 1997 with a further 150 diamond and RC drill holes completed. Kagara commenced mining at Mt Garnet in 2002 with open pit and underground mining operations producing 484 kt at 6.9% Zn and 0.45% Cu from the open pit and 600 kt at 10.3% Zn, 0.35% Cu from underground activities. The underground mine at Mt Garnet was placed on care and maintenance in September 2011 with the processing plant continuing to treat ore until April 2012, at which time it was also placed on care and maintenance. Kagara suspended mining operations on 24 April 2012 and announced entry into Voluntary Administration on 30 April 2012.
Snow Peak Mining purchased the Mt Garnet Mine and Surveyor Mine in January 2013. The Mt Garnet and Surveyor mines were reopened in March 2014 (under management of CSD), and approximately 975,000 tonnes of ore was processed at Mt Garnet from both Mt Garnet and Surveyor mines with more than 126,000 dmt of base metal concentrates sent to overseas ports via Townsville port.
Mining recommenced on remnant stopes within the Mt Garnet underground in June 2017. The Mount Garnet concentrator was partially refurbished and restarted in July 2017.
Exploration and Underground Development
In April 2016, CSD acquired the assets of Snow Peak Mining Pty Ltd (SPM), including the Mt Garnet underground mine.
In late 2017, CSD commenced development to access the newly discovered ‘Mt Garnet Deeps’ deposit adjoining the Mt Garnet underground mine. Initial drilling from surface had returned favourable results and two further drilling programs from surface provided the Company with sufficient information to commence mine design and planning.
Remnant mining of the existing Mt Garnet underground continued in parallel with new development to access Mt Garnet Deeps.
Mount Garnet Base Metal Project – Looking West
Mt Garnet Base Metal Local Geology
The Mt Garnet base metal mineralisation occurs in a garnet-pyroxene-amphibole skarn-altered, northerly-trending, fossiliferous limestone and limey siltstone unit that hosts sphalerite-rich mineralisation. The skarn zone dips sub-vertically, is typically 30 metres to 60 metres wide, and extends beyond 550 metres below surface, which is the current limit of drill investigations.
High-grade massive and semi-massive sphalerite-rich mineralisation (notionally >10% Zn) is largely confined to two distinct, sub-parallel, shallow to moderately north-plunging “shoots”, termed the South Shoot and the North Shoot. The South Shoot was mostly extracted during the open cut phase of mining, completed by Kagara in 2008. The North Shoot ore-grade mineralisation has been tracked down-plunge for about 550 metres from 4600 mN to 5100 mN in horizontal projection. The North Shoot was extracted by Kagara, SPM and CSD.
Mount Garnet Geology
Mt Garnet Deeps JORC Resources
Mt Garnet Deeps Resources
The Mount Garnet Deeps base metal project resources were updated in July 2019 to comply with the JORC 2012 reporting guidelines.
The resources are reported above a 2% Zinc cut-off grade with the resources summarised below
Mt Garnet Deeps- Resource Summary as at August 30th 2019
Mount Garnet Deeps – Exploration Target/Exploration Upside
Further drilling of the Mount Garnet Deeps was undertaken in August 2018 from an underground platform off the decline development once it reached the mineralized area and 16 diamond drillholes were completed for this program.
A total of 13,407m from 54 diamond and RC pre-collared diamond drill holes were drilled by CSD between 2017 and 2018. Of these 54 holes, 3 of them were abandoned due to hole deviation issues. Examples of significant results that intersected the Mount Garnet Deeps mineralized domain are summarized in the table below:
Examples of Mount Garnet Deeps Significant Intercepts from CSD Drilling
The locations of the Mount Garnet Deeps significant drilling results are shown in below.
Mount Garnet Deeps – Significant Drilling Results
Mount Garnet Exploration Targets showing Planned Holes (Blue Traces) – Long Section Looking West
Current Mining Activity
Current mining activity is occurring at both the Mt Garnet Mine and the Dry River South (DRS) Mine at the Surveyor Project.
Mt Garnet Deeps Mining Activity
Development of the new Mt Garnet Deeps decline continued during the last quarter of FY2019 in parallel with ore drive development. Ore from the old Mt Garnet Mine continued with small quantities of remnant ore from the upper levels.
Increasing quantities of development ore will continue to be mined from the Mt Garnet Deeps deposit with stope production commenced in the first quarter of FY2020.
Extraction of Mt Garnet Deeps underground employs Longhole Open Stoping as the mining method with 20 m to 25 m level spacing. Development is achieved using CSD owned Atlas Copco M2D twin boom Jumbos. Longhole production drilling is achieved using CSD owned Sandvik DL432i Production Drill. Teleremote loading in stope is done by CSD CAT R1700 and R2900 loaders and ore is hauled to surface using CSD CAT AD55 articulated dump trucks.
Mount Garnet Proposed Exploration
Exploration planned for the Mount Garnet project area includes underground diamond drilling to target potential extensions of the Mount Garnet Deeps deposit, underground drilling of the Mt Garnet Central Deeps Project and drilling along strike at a prospect called Mt Garnet Dam prospect . Drilling is also planned at the Jessies dream prospect where repeats of the Mount Garnet deeps style of mineralisation potentially occur. These prospects are shown below.
Mount Garnet Exploration Prospects