Box Hole (EL 32419), Northern Territory
King’s Lead-Zinc mine historically produced 15t of galena with an average grade of 66% Pb, 58.50 g/t Ag and 0.43% Bi
The Box Hole project is located within the Barkly Region of Northern Territory and covers an area of approximately 12,708 ha and the maximum distance across the project is about 8.5 km east–west and 15 km north–south.
The nearest historical mine is the inactive Harts Range garnet mine (approximately 120 km to the southwest) while the Molyhil tungsten-molybdenum project (Thor Mining PLC) is approximately 40 km to the south.
Exploration and Mineralisation
Box Hole prospect, stratabound surface mineralisation with MVT characteristics can be mapped discontinuously for 6.5 km along strike. The mineralised interval lies immediately above the constituent Eurowie Sandstone Member and stratigraphically just below a stromatolitic interval several metres thick.
Box Hole mineralisation is best exposed in and around Kings Workings, where galena cubes up to 4 cm across occur in a grey silicified carbonate. One of the stromatolitic reefs in the Arrinthrunga Formation hosts the Kings Workings deposit which was mined for coarse galena in a small scale artisanal operation in the early 1960s (NT Open File Report CR2009-0822). MVT-style barite-galena mineralisation formed during expulsion of deep basinal brines during Alice Springs Orogeny (Devonian–Carboniferous) (NT Open File Report CR2009-0822).
Previous exploration in the Box Hole tenement has located several galena occurrences with artisanal mining occurring in the early 1960’s.
In 1992, CRAE drilled one hole (DD92TC1) close to Kings Workings. The lowest sandstone unit is logged in the 78–80 m interval. Below this interval, only interbedded dolomite, dolarenite and dololutite are logged. Siderite is common, sometimes in association with pyrite. Green chlorite is also logged. Bitumen is logged deeper in the drill hole and fluorite is also recorded.
In 2007, a dipole-dipole IP survey was conducted over approximately half of the project tenement, including the southern mineralised zone. It consisted of 18 lines at 50 m and 100 m electrode spacing, for a total of 27.9 line kilometres (Mackay and Reynolds, 2009). The IP results were interpreted to indicate two chargeable layers (outer and inner). The inner chargeable layer is coincident with the Kings Workings mineralisation, and the outer interpreted to correlate with the northern mineralised zone. Drilling of shallow IP targets suggests that the anomalism can be attributed to pyritic shale (Mackay and Reynolds, 2009). The deep IP targets in the northeast of the tenement (Lines 2, 3 and 7) have not been drilled. Drill hole DD92TC1 probably intersected the deep IP anomaly in line 22 without intersecting significant mineralisation (Mackay and Reynolds, 2009).
In 2008, Uramet Minerals Limited undertook ground gravity and IP surveys over Box Hole in an attempt to identify the presence of disseminated metal sulfide bodies at depth (NT Open File Report CR2008-0387). The company also drilled 94 rotary air blast (RAB) holes for a total of 4,155 m (~44 m average depth) in order to test a number of possible targets based on geophysical, geochemical, and mapping data, mainly along the line of known mineralisation (Mackay and Reynolds, 2009). Holes that were drilled away from the mapped mineralisation returned low (below hand-held XRF detection limits) Zn and Pb values (Mackay and Reynolds, 2009).