A fifth drilling phase is in the works for Estrella Resources (ASX: ESR) to follow up the Broonhill massive sulphide discovery it made by last month at its Carr Boyd nickel project, north of Kalgoorlie in Western Australia.
The explorer announced the discovery in late October after a reverse circulation (RC) hole drilled during its current phase four program intersected 12 metres of nickel-copper sulphides including 2m of basal massive sulphides.
The zone was uncovered at Broonhill, 1.4 kilometres north of the T5 massive sulphide discovery and is hosted by the same pyroxenite basal unit as the T5 sulphides.
Estrella managing director Chris Daws said the intersection was reminiscent of results returned from a 2019 RC hole.
“It was this historic hole that led the company to drill and locate the T5 massive sulphides at depth, so we are particularly encouraged by what may come of this find,” he said.
“In addition, the intersection of further nickel-copper sulphides in an area which already hosts the historic Carr Boyd mine and our T5 discovery illustrates the significant potential of this region for discoveries.”
Less than a week after the Broonhill discovery, Estrella uncovered three additional zones of nickel-copper sulphides containing significant widths of massive sulphides with accompanying globular, highly disseminated, disseminated, stringer and cloud sulphides.
“It seems every time we put another exploration hole down, we hit more nickel-copper sulphides and on this occasion a completely blind massive nickel-copper sulphide intersection below T5,” Mr Daws said.
“I have always believed that Carr Boyd could deliver a world-class orebody and it’s not disappointing me at this stage. I look forward to what is uncovered next,” he added.
Expanded exploration plans
Mr Daws said Estrella plans to expand its phase four exploration program to gain a better understanding of this emerging region and commence a phase five diamond drilling campaign “early next year”.
According to the company, the Broonhill discovery has significantly increased the likelihood for more massive sulphide intersections on the Broonhill-T5 basal contact. With 2km of the basal contact explored by Estrella to a depth of 280m, there is still another 2km of this contact to be drilled during phase four.
Phase five will test any phase four anomalous or intersection results with diamond core and down hole electromagnetic (DHEM) data, down to a depth of 900m (potentially deeper depending on initial results) through a staged approach.
CSIRO to initiate Carr Boyd studies
Three nickel experts from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) are working with Estrella geologists to initiate studies on the age, formation and characterisation of the Carr Boyd Igneous Complex as well as study the formation and modes of mineralisation at T5, Broonhill, Tregurtha and the historical Carr Boyd mine.
This work will aid in Estrella’s vectored exploration model and risk-based approach as the company expands phase four and begins planning its phase five exploration programs.
Estrella’s flagship project covers the Carr Boyd Layered Complex, a 75-square-kilometre mafic igneous complex which hosts several nickel and copper sulphide occurrences including the historic Carr Boyd Rocks mine.
Until this year, very little work has been conducted at Carr Boyd since the 1970s.
The company also holds the Spargoville project, southwest of the goldfields mining town of Kambalda. This area contains a number of deposits discovered from the late 1960s onwards including 5A, a high-grade body of nickel, copper and cobalt located directly below the floor of an open pit mine.