Diamond core from the seven-hole program was submitted for gold and multi-element analysis after indicating both epithermal gold and gold-rich volcanogenic massive sulphide (VMS) mineralisation.
All holes intersected significant gold intervals associated with sulphide mineralisation in a variety of geological styles.
While providing further geological insights, the results demonstrate a pathway for an upgraded mineral resource estimate at Lewis, as well as a simplified Lewis pit and incorporation into the Cardinia process plant design.
Highlighted results from within potassic altered basalt within the epithermal system include: 19.9 metres at 1.84 g/t gold from 17.4 metres; 32.4 metres at 1.16 g/t from 39.6 metres; 37.2 metres at 1.04 g/t from 51.4 metres.
Evidence of VMS mineralisation in this system with gold-rich massive and banded sulphides in felsic volcaniclastic sediments was also encountered.
Intersections from within the sediments include: 4.8 metres at 17.6 g/t from 48.6 metres; 0.5 metres at 127.8 g/t gold, 115 g/t silver, more than 10% sulphur and 76 g/t tellurium; and 0.7 metres at 6.6 g/t gold, 36.5 g/t silver, 8% sulphur and 7 g/t tellurian from 96 metres.
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The diamond drilling aimed to replicate previous reverse circulation (RC) intersections and confirm the style of mineralisation encountered at Lewis in fresh rock.
Previous RC drilling had encountered gold over broad intersections greater than 30 metres with generally lower grade mineralisation of 0.5 to 1.5 g/t and occasionally bonanza assays greater than 30 g/t over 1 metre associated with extensive mafic-felsic rock contact.
Several styles of mineralisation were encountered in the recent program, usually associated with varying amounts of sulphide with attendant precious and base metals anomalism.
Distinctive textures and alteration indicate a near-surface mineralising environment consistent with sub-marine VMS and/or epithermal gold-mineralising environments.
Lewis was previously interpreted to be supergene gold in the oxide and transition zones above a poorly-defined primary source of mineralisation.
Previous drilling was almost exclusively reverse circulation and aircore with limited drilling into the underlying fresh rock zone below 60 metres depth.
Detailed logging of Lewis’ core has identified mineralisation styles commonly associated with VMS deposits, low sulphidation epithermal gold deposits and, as Alto had expected, greenstone-hosted orogenic gold deposits.
Multi-element assays from the remainder of the drill cores are being processed and are expected to be delivered over the next several weeks.
Follow-up diamond drilling is scheduled to begin in the week starting December 10, focusing on further definition of the various mineralisation styles at Lewis.
The drilling will also extend mineralisation down-dip within the Lewis pit design, the broader zones of low-grade epithermal mineralisation and within the deeper, higher-grade VMS-style mineralisation.
An additional six diamond holes are planned with potential for a further five should Kin encounter notable mineralised zones.
Metallurgical work is underway for the initial seven holes to determine the amenability of the gold and other metal mineralisation standard carbon-in-leach treatment.
Further test work is also planned to assess the preferred treatment approach to the sulphide-rich other metal mineralisation.