The Board of Thor Mining Plc (“Thor” or the “Company”) (AIM, ASX: THR), is pleased to announce an upgraded and increased mineral resource estimate containing tungsten, copper and now zinc, for the Desert Scheelite deposit at Pilot Mountain in Nevada USA.
· The Desert Scheelite mineral resource estimate now comprises 10.7 million tonnes at 0.26% WO₃, 19.38 gram/tonne Silver (Ag), 0.15% copper (Cu), & 0.38% zinc (Zn) (above cut-off grade of 0.15% WO3) (Refer to Table A below);
· The upgraded mineral resource estimate represents a 6.5% increase in the scheelite inventory for Desert Scheelite, now containing 27,700 tonnes of WO₃ (tungsten trioxide) 85% of which is in the Indicated category;
· For the first time, the estimate includes zinc in the resource inventory, contributing an additional potential by-product stream to the project;
· The planned flotation recovery process, currently being trialled, is likely to recover zinc sulphides into concentrate with minimal additional cost;
· The resource inventory still has considerable growth potential via the Gun Metal and Good Hope deposits, as well as further potential upside at both Desert Scheelite and Garnet;
Mr Mick Billing, Executive Chairman, commented:
“This addition to the resource estimate at Pilot Mountain further enhances the potential of this exciting project.”
“Pilot Mountain hosts a large and, in the directors’ view, valuable tungsten resource in the USA, where there has been no primary production of tungsten for some years, despite being classified as a critical mineral by the US Department of the Interior.”
“I look forward to outlining the next steps for this key Company project in the coming weeks. This update will complement comprehensive updates across all areas of our operations in what is a highly proactive period for Thor.”
“In this regard I also expect to provide updates to the market in respect of Molyhil commercialisation, the Bonya project review exercise (including vanadium) and the latest developments in respect of the Company’s Kapunda copper project interest.”
Further opportunities for the growth of the Garnet resource are being evaluated for follow up drilling.
*Exploration Targets are conceptual in nature and there is insufficient data to define a Mineral Resource under the JORC Code. It is uncertain if further exploration will result in the determination of a Mineral Resource.
Summary of Resource Estimate and Reporting Criteria
The work is an update of the resource completed by Golder Associates in 2012. The 2018 resource update was undertaken by Resource Evaluation Services (RES)
Drilling of the Desert Scheelite deposit has been conducted in campaigns since 1972, with the most recent drilling completed in 2017. The update to the resource includes four new diamond drill holes completed by Thor and seven additional drill holes added to the database from historical sources.
The drill hole database used for the Desert Scheelite resource estimation was provided to RES as the MS Access database ds_drillhole_database.mdb. The referential integrity of the supplied database was confirmed, and the database validated against the 2012 resource database. Adjustments to the database were made by RES correcting the imperial to metric conversion and standardising the database to millimetre precision.
The Vulcan ISIS database ds112018.geo.isis was created by RES for the update. The resource model update is based on 99 drill holes for a total of 18645 m, spaning 750 m east to west and 300 m in a north to south.
Most of the modelling data from the Golder 2012 model was available to RES including the topographic and mineralisation models.
The mineralisation wireframe models were adjusted to account for the additional drilling. The mineralised skarns were separated into several domains representing structural and geological differences. The Desert Scheelite deposit has been modelled as several sub-vertical lenses. The Desert Scheelite deposit trends dominantly east-west and dips variably 70-80º.
The mineralised skarns have been modelled using a 0.1% WO3 cut-off and geological logs when available. The quartz monzonite, tertiary volcanics, metaclastites, hornfels and Top of Fresh Rock have been interpreted using the logged stratigraphy codes. The mineralised zones were used to define spatial regions for statistical and geostatistical analysis.
For statistical data analysis, exploration data was composited to 1.52 m (5 ft) downhole lengths. Imprecise imperial to metric conversion factors resulted in a significant proportion of short composites. To mitigate this issue length weighted raw samples were used in the final analysis and estimation.
Analysis was based on four assay variables: WO3, Ag, Cu and Zn. The composites were flagged to the geological interpretations and statistical analysis performed by domain.
Downhole and directional grade variography was completed for all domains to provide parameters for the Ordinary Kriging method used for resource estimation. The spherical scheme model was used to obtain all variogram parameters from the experimental variograms. The modelled variograms have directions consistent with the orientations of the lodes and exhibit a low angle plunge in the main skarn.
Four estimation passes using increasing search distances were employed to interpolate all the blocks within the skarn and waste domains. The fourth pass was used to establish inferred resource down dip of the deposit by increasing the search ellipse size in the down dip direction.
Density values were applied to model based on the Golder 2012 work.
The information contained within this announcement is deemed to constitute inside information as stipulated under the Market Abuse Regulations (EU) No. 596/2014. Upon the publication of this announcement, this inside information is now considered to be in the public domain.
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