Ad Duwayhi lies within the Afif composite terrain in the central Arabian Shield. The Afif terrain consists of a complex assemblage of volcanic arc sequences and a continental microplate that are overlain by successor-basin volcano-sedimentary sequences (Bani Ghayy and Murdama Groups). All these rocks were intruded by post-tectonic granitic rocks.

The deposit lies at the southern end of a zone of Pre-Cambrian volcano-sedimentary rock, which have been overprinted by greenschist facies metamorphism. The deposit is located to the north of a fault bounded belt of folded meta- sediments and plutonic rocks. A granodiorite body lies to the east of the deposit, with the deposit stratigraphy cut by multiple intrusive dykes and sills of dolerite, rhyolite, porphyritic granite and a polymict breccia pipe.

The main mineralisation is associated with a curved thrust structure with an average strike of 045° and dip of 45° southeast, curving from a northerly direction in the southwest to an easterly direction in the northeast. There are other more minor mineralised structures on different trends.

Hydrothermal alteration is common across the deposit area comprising silicification (everpresent), quartz-sericite-pyrite, potassic and propylitic. The quartz-sericite-pyrite alteration is most closely associated with the gold mineralisation.

The main mineralisation is structurally controlled by the curved thrust structure, with a thrust zone typically betw ........

Mine access to the open-pits is via a single haul road developed as part of the starter pit and the final pit and extending from surface to a depth of 145m below surface. The open-pit is designed with the following parameters: 20m wide ramps with a gradient of 10% and overall slope angles ranging from 45° to 58°. Other final design aspects are: bench heights of 15m; batter angles of 75°; and berm widths of 8m.

Mining methods comprise standard drill-blast-load-haul. Mining occurs by drilling and blasting 5m high sub-benches with 120mm to 200mm blast holes. Hydraulic excavators with 8.4m3 bucket capacities load blasted ore and 10.0m3 bucket capacities load waste into 80t rear-dump haul trucks. Additional service equipment comprise graders, tracked dozers, water trucks and general service vehicles.

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