Crocodile Gold - Maud Creek
Maud Creek is located approximately 285 kilometres south-southeast of Darwin and hosts a significant remaining resource. It is open at depth and along strike. The mineralized material is refractory, containing arsenopyrite, and would require additional study before becoming part of Crocodile Gold's development plan.
The Maud Creek deposit is hosted by rocks belonging to the Tollis Formation which consists of interbedded greywacke, siltstone, phyllite and tuffs. This formation is intruded by the Maud Dolerite. Quartz veining with associated gold mineralization occurs within this intrusive and in the adjacent sediments.
The resource is located along a steep easterly dipping, north-south trending fault which forms the contact between lithic sandstone and siltstone to the west and mafic tuff to the east. Gold mineralization is associated with intense quartz veining along the contact. Structural features such as shears, faults, associated brecciation, geological contacts and competency contrast between the different rock types principally control the mineralization associated with the Maud Creek deposit.
Widths of mineralization are usually influenced by the intensity of deformation such as shearing, faulting and associated brecciation. This may range from several metres to 50 metres in true width.
The principal portion of the deposit is 250 metres long, up to 57 metres wide, striking north and dipping at 60° to the east. The strike extensions of this mineralized Main Zone lode are open to the north where previous near-surface drilling over a 800+ metre strike length has intersected a similar style of mineralization, though at lower grades and widths.
The orebody is typically oxidized to a depth of 15 to 20 metres, then moderately oxidized (Transition Zone) from 25 to 30 metres passing abruptly to fresh sulphide ore. Primary mineralization contains up to 5% total sulphides, dominantly pyrite and arsenopyrite. Arsenic levels within the higher grade gold zone may range up to 2%. Testwork has shown that the bulk of the primary mineralization is refractory in nature; hence recovery of the gold by conventional direct cyanidation processes is not possible.
Maud Creek has been extensively drilled with over 65,000 metres of drilling completed over the project's history. Importantly, several structural targets have been identified that may represent repetitions of the lode. These target zones which have not previously been recognized require drill testing.
In addition to the deep exploration potential there is immediate near-surface potential relating to a possible expanded open pit operation.
Due to the refractory nature of the mineralization at Maud Creek, treatment of the material requires additional testwork. With conventional milling, studies have shown the recovery would be approximately 20%. However, with sulphide flotation, the expected recovery is 95%.
Metallurgical test work indicates that 95% recovery of the contained gold is possible by producing an arsenopyrite rich flotation concentrate. There is potential for this concentrate to then be processed elsewhere.
Extensive metallurgical test work has been undertaken at Maud Creek, beginning in 1998 by Kilkenny Gold, which indicated the bulk of the Maud Creek ore was refractory in nature. GBS Gold undertook extensive analysis to investigate the refractory nature of the mineralization at Maud Creek and the viability of mining.
Crocodile Gold will investigate other processing options for Maud Creek ore.
Maud Creek includes the historic Gold Creek gold deposit located along the Gold Creek fault. Gold mineralization is associated with intense quartz veining along the contact. Maud Creek was previously mined as an open pit operation in 2000 with ore shipped for treatment off-site. A substantial amount of historical drilling has taken place at Maud Creek from the mid 1960s to 2006. Several studies were also completed evaluating the processing of oxide, transitional and sulphide ore.
Maud Creek was previously owned by Harmony Gold and Terra Gold Mining until GBS acquired the asset in 2006.