Thor Mining (ASX, AIM: THR) has announced a 55% tungsten resource inventory increase at the company’s wholly owned Pilot Mountain tungsten project in Nevada, USA (figure 1), representing a maiden resource estimate for the Garnet prospect, and an increase in the resource estimate at Desert Scheelite.
Following drilling in March this year, an inferred resource estimate for the Garnet deposit has been completed comprising 1.83 million tonnes (Mt) at an average grade of 0.36%WO₃ (using cut-off grade of 1,000 ppmWO₃).
Further, a re-evaluation of the Desert Scheelite deposit has resulted in an upgrading of the resource estimate to 9.9 million tonnes at an average grade of 0.26%WO₃, 19.39 gram/tonne Silver (Ag), and 0.14% copper (Cu)(using cut-off grade of 1,500 ppm WO₃, previously 2,000ppm).
The total Pilot Mountain resource inventory now stands at 11.73 Million tonnes at 0.28%WO₃ (Table 1).
Table 1: Pilot Mountain Resource Summary 2017 (JORC 2012) – 100% owned by Thor Mining Plc
Note: All figures are rounded to reflect appropriate levels of confidence. Apparent differences may occur due to rounding.
Mr Mick Billing, Executive Chairman of Thor: “This is a significant step forward for the Pilot Mountain project. The resource inventory still has considerable growth potential via the GunMetal and Good Hope deposits, as well as more potential upside at Desert Scheelite and Garnet”
“Importantly, the grade of mineralisation at Pilot Mountain is relatively high and this underpins the robust nature of the project.”
Figure 1: Pilot Mountain Location
Six holes were drilled to validate historic drill data from Union Carbide Corp drilling undertaken in the 1970’s (Figure 2).
Significant intercepts include:
- 3.8m @ 0.31%WO₃ and 2.2%Zn from 4.6m
- 3.8m @ 0.72%WO₃ and 1.6%Zn from 45.0m
- 5.3m @ 1.0%WO₃and 0.9%Zn from 83.1m
- 6.1m @ 0.24%WO₃ from 16.5m
- 14.5m @ 0.31%WO₃, 0.3%Zn from 25.9m
Figure 2: Map of the Garnet and Gunmetal prospect area. The 2017 Garnet drill holes tested less than a third of the total historic drill data over the entire Garnet and Gunmetal area.
Zinc grades from the 2017 drilling appear sufficient to produce a saleable bi-product to the Scheelite stream. Assays for zinc are not available in the historic database and the 2017 drilling zinc data alone is insufficient to estimate an inferred zinc resource. On the basis of the 2017 drill data, the following zinc exploration target* has been derived for the Garnet deposit:
1.4 – 1.8 Mt at 0.5 to 1.0% Zinc
(7,000 – 18,000 tonnes contained Zn metal)
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.
Desert Scheelite Deposit
Following a review of the Desert Scheelite deposit and a comparison with the Garnet deposit where a WO₃ cut-off grade of 1,000ppm was applied, it was decided to amend the Desert Scheelite resource cutoff grade to 1,500ppm WO₃, from the previously applied 2,000ppm WO₃.
About Pilot Mountain
Thor’s Pilot Mountain Project, acquired in 2014, is located approximately 200 kilometres south of the city of Reno and 20 kilometres east of the town of Mina located on US Highway 95.
The Pilot Mountain Project comprises four tungsten deposits: Desert Scheelite, Gunmetal, Garnet and Good Hope. All are in close proximity (~three kilometres) to each other and have been subjected to small-scale mining activities at various times during the 20th century. Union Carbide acquired the project in 1978, for US$7.0 million (estimated at US$26million – US$40million in 2017 dollars), and conducted detailed exploration and feasibility activities until, following a global downturn in the tungsten industry in the 1980s, they suspended further work.
Figure 3: Drilling at Desert Scheelite