• Terra Metals maiden drilling at Onslow has returned up to 1060g/t silver and 0.99% tungsten
  • Intersected high-sulphidation epithermal alteration was unexpected as drilling was testing for IOCG mineralisation
  • Data review underway to determine mineralisation model and potential for a porphyry source


Special Report: Maiden diamond drilling at Terra Metals’ Onslow project delivers high-grade results of up to 1060g/t silver and 0.99% tungsten.

The result from the first pass drilling, which was co-funded by the WA state government under its Exploration Incentive Scheme, is especially intriguing given that it was returned from a frontier province.

Historical exploration at the 576km2 project in the northwestern extension of the Capricorn Orogen had focused almost exclusively on the hunt for iron in the cover sequence, leaving the ‘basement’ essentially untested.

A review of historical airborne electromagnetic (EM) surveys by Terra Metals (ASX:TM1) confirmed several anomalies that have never been drill tested.

Nearby historical exploration has also identified the potential for Onslow to host banded-iron-formation hosted gold and iron-oxide hosted copper-gold mineralisation (IOCG).


The northern Onslow project area with OND003 drill intercept. Pic: Terra Metals


“Unexpected” mineralisation style

Partial assays from the three hole diamond drill program totalling 1283m have returned a high-grade 1m intersection of 1060g/t silver, 0.99% tungsten and 0.23% copper from 160m at the top of a broader 6m zone at 179g/t silver.

This mineralisation is hosted within an interpreted high-sulphidation epithermal alteration zone.

Such systems are known to produce large high-grade silver deposits globally and are often linked to a deeper mineralised porphyry source.

Where it gets interesting for TM1 is that the intersected mineralisation was unexpected as the drill program was originally testing for IOCG mineralisation.

Additionally, hole OND003 sits on the edge of an untested EM anomaly defined by TM1’s 2022 airborne EM survey.

This anomaly is a 600m by 120m conductive body that will now be reviewed in light of the newly identified mineralisation.

“Intercepting high-grade silver mineralisation is a great result for a first pass reconnaissance drilling program in a frontier province,” managing director Thomas Line said.

“We are aware of an untested EM anomaly just to the south of the high-grade silver mineralisation and we are now reviewing available datasets to determine a model for high-sulphidation epithermal silver mineralisation, and the possibility of a porphyry source.”

TM1 will undertake petrology work to further characterise the geological zone and mineral deportment.



This article was developed in collaboration with Terra Metals, 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.