Drilling has expanded the footprint of Lefroy’s Burns copper-gold zones in all directions while identifying three new zones of mineralisation.

Final results from the 28-hole reverse circulation and diamond tails program that was completed during the March quarter also extended the mineralised Eastern Porphyry, which remains open, by 120m north from the baseline section.

Burns has now been defined over 300m from north to south and 200m east to west with mineralisation remaining open in all directions.

Lefroy Exploration (ASX:LEX) noted that the top results from the four deeper diamond drilling sites are 29.1m grading 2.64 grams per tonne (g/t) gold and 0.18 per cent copper from a depth of 277.4m in LEFR273 and 48m at 0.39g/t gold and 0.41 per cent copper from 146m in LEFR 272.

These holes defined two new, separate, and significant intervals of copper-gold mineralisation that remain open.

The company notes that the mineralisation in LEFR273 is a new and unexpected mineralised zone within basalt that contains a narrow but very high-grade interval that is interpreted to be from a near vertical structure that has continuity up-dip to previous shallow RC holes on this drill section.

This new interval is open to the south and may represent a new style of mineralisation at Burns.

Six angled RC holes drilled within the Eastern Porphyry in March as pre-collars for later diamond tails also returned significant results such as 48m at 0.59g/t gold and 0.31 per cent copper from 84m and 39m at 0.55g/t gold and 0.28 per cent copper.

Mineralisation intersected in these holes is interpreted to be part of an outer halo that is peripheral to a higher-grade component of the Eastern Porphyry further down-hole.

Resampling work

Lefroy has also completed the resampling that has confirmed and better defined the higher and lower grade zones intersected by the earlier 22 reverse circulation holes in the same program.

This is expected to assist with the determination of the geological settings for the copper-gold mineralisation.

One notable result is from hole LEFR260 which was previously reported as a 60m interval grading 5.22g/t gold and 0.38 per cent copper from 112m to end of hole, including 20m at 12.2g/t gold and 0.87 per cent copper from 144m.

Resampling has improved this to 38m at 7.63g/t gold and 0.56 per cent copper from 134m to end of hole, including 27m at 10.1g/t gold and 0.74 per cent copper from 141m.

Meanwhile, resampling of LEFR270 has outlined a new zone of copper-gold mineralisation that may reflect supergene mineralisation from the magnetite pyrite altered basalt intersected about 120m to the south, providing a new and additional target area for follow-up.

Current and upcoming activities

Diamond drilling is now underway at Burns with the first hole being designed to twin and then extend the zone around LEFR 260.

A further 14 holes are planned under this current program, with total length of drilling to exceed 2000m.

Other work to support further evaluation includes:

  • Development of a 3D geological and gold and copper model;
  • Detailed gravity survey scheduled for May to assist in mapping rock density contrasts;
  • 3D modelling of prior ground magnetic data and newly acquired gravity data to produce an integrated geophysical model to guide drilling;
  • Submission of selected drill samples for full suite multi-element analyses to assist in development of a 3D geochemical model to guide drilling and characterise rock types; and
  • A heritage survey on Lake Randall is scheduled for June 2021



This article was developed in collaboration with Lefroy Exploration, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.