Core Exploration’s newly granted Yerelina tenement, EL 5015, covers close to 1,000 square kilometres adjacent to the Company’s Fitton Project in northern South Australia
This newly granted tenure is also highly prospective for shallow base and precious metal mineralisation (Table 1 and 2).
Four historical workings, operating in the late 19th and early 20th century, are recorded from within EL 5015. These old workings are located in an apparent east – west trend over 8 kilometres (Figures 2, 3 & 4). The limited documented information about the historical workings indicates that high grades of silver (Ag) and lead (Pb) were mined. Core’s mapping and sampling around and along strike from these workings has confirmed silver, lead and zinc mineralisation.
Core’s analysis of modern satellite imagery and the Company’s recently completed detailed heli-borne magnetic and radiometric survey data has identified that these workings are hosted by a large scale system of repeated north/south regional structures over many kilometres (Fig 2 & 3).
Initial Investigations on EL 5015
Core has undertaken reconnaissance mapping and sampling within the new EL 5015. To date, the Company has visited three of the four historical workings and confirmed that they are associated with north – south striking iron rich gossaneous breccias that appear to have in filled fractures that cross cut the Adelaidean Tapley Hill Formation strata (Figure 1).
Core identified up to 10 historical shafts at the Great Gladstone workings that appear to be up to 30m deep (Figures 1 & 5). Great Gladstone is recorded to have produced high grade silver and lead. Recent field mapping has also identified surface expressions of secondary copper oxide (malachite, azurite). Primary sulphides in existing mullock heaps indicate primary mineralisation at depth. Sampling of the mullock heaps as well as from in situ iron rich gossan produced assay values up to 11.27 % combined lead (Pb) + zinc (Zn) and up to 203 g/t silver (Ag) (Table 2).
The Great Gladstone workings are aligned north – south over approximately 1km and have been dug into a semi continuous 0.5m to 2.5m wide iron rich brecciated gossan. Furthermore Core observed that the iron rich breccia is found to not only occur infilling north – south fractures, but also extend along the east – west bedding planes of the Tapley Hill Formation. This observation provides a mechanism for the mineralising fluid to have travelled and accumulated at depth, layer parallel to stratigraphy.
Initial investigations at the Emily workings identified two historical shafts 50 metres apart both dug into an, up to 2m wide, north – south striking iron matrix rich breccia filled fault. Samples from the Emily working assayed at up to 13.34% combined Pb + Zn.
The Big Hill workings are comprised of a single drive shaft into a significant iron rich breccia gossan. This gossan is up to 250m long, striking north – south and up to 20m wide pinching out at both the northern and southern ends. This is the most significant outcropping gossan identified by Core at this stage. Samples taken from the historic workings at Big Hill as well as from along the gossaneous outcrop assayed at up to 2.35% combined Pb + Zn with the majority of samples from the large gossan above 1% combined Pb + Zn.
Core completed a heli-magnetic survey over the historical mine areas on EL 5015 at the same time as the adjacent Fitton EL 4569 in an attempt to map the faults that have been identified as hosting the mineralised Pb + Zn + Ag mineralisation. Preliminary interpretations of the data indicate that there is a strong correlation between the magnetics and the known distribution of the faults from the reconnaissance mapping (Figure 2). This correlation will be used to develop further sampling targets in the area.
Table 1. Summary of best results of reconnaissance sampling of 3 historic mine workings, EL 5015
Table 2: Rock chip assays from EL 5015 Yerelina with combined lead and zinc assays above 1%
Notes to Table 2:
Au: FA25//AA Lead Collection Fire Assay:
Ag, Pb: 4A/MS 4 Acid Digest Mass Spectrometry:
Cu, Zn: 4A/OE 4 Acid Digest Inductively Coupled Plasma Optical Emission Spectrometry
The presence of this mapped surface mineralisation and alteration may or may not extend at depth and this can only be confirmed by drilling