Castillo Copper Ltd (LSE:CCZ, ASX:CCZ) has wrapped up four drill holes for 516 metres at Fence Gossan prospect, part of a larger campaign at the BHA Project’s East Zone near Broken Hill in Far West New South Wales, and is pleased with initial observations and interpretations.
While final assay results are pending, Castillo’s geology team believe there is potential for cobalt along with copper-gold, rare earth elements (REE) and platinum group elements (PGE) mineralisation.
Positive geological sequence
Cobalt mineralisation zones were hit across the four drill holes, with geological sequences intersected consisting of clay, amphibolite, schist, gneiss and pegmatite that appear to be dipping moderately.
The company logged numerous disseminated sulphide layers – mostly pyrite linked to amphibolite, up to 17 metres thick – which could potentially host cobalt mineralisation.
Similar to findings at the Tors Tank prospect, the geological interpretation suggests consistency with observations noted by previous explorers, including North Broken Hill in the 1970 and 80s.
Backing these findings up, XRF field observations also indicated cobalt mineralisation.
Cobalt, REEs and PGEs
The company welcomes these positive interpretations, which imply that the underlying geology has the potential, subject to final assays, to host cobalt, REEs and PGEs.
This interpretation is largely based on recent re-assays of diamond core from a drill hole at the Iron Blow prospect.
Just like the Iron Blow prospect, there are significant magnetite-rich zones – associated with pegmatite up to 19 metres thick – which potentially hosts REEs and, based on field XRF observations and subject to final assays, platinum group elements (PGEs).
The comparable geology suggests the presence of high-grade REEs within the BHA Project’s East Zone.
The best intersection was 8 metres at 1,460 parts per million (ppm) total rare earth oxides (TREO).
Pyrite means cobalt
During the qualitative logging process, the company identified multiple disseminated sulphide layers – mostly pyrite – up to 12 metres thick.
This is significant, as previous work by North Broken Hill tells us that pyrite hosts cobalt mineralisation.
Further analysis of the samples showed that pyrite is mostly associated with amphibolite layers and, thinner, sparser horizons which occur and are spread within interbedded schist and gneiss layers.
In addition, supporting the interpretation that cobalt mineralisation is apparent, but subject to final assay confirmation, field XRF observations indicated positive readings within the amphibolite zones.
All reverse circulation (RC) samples from the Fence Gossan prospect have been dispatched to the lab in Adelaide for further analysis, with results due back in several weeks.
Castillo Copper managing director Dr Dennis Jensen said: “With the drilling campaign at the halfway mark, the board is optimistic that known mineralisation at the Tors Tank and Fence Gossan prospects has potentially been extended.
“Moreover, for Fence Gossan in particular, the board is delighted to note the significant pegmatite intercepts which have the potential to host REEs as well as PGEs.”