Twice the size: Doubling of silver resource is a big step forward for Thomson

Thomson has defined a maiden resource of 19.5Moz silver equivalent at its Texas District deposits, nearly doubling its total inventory to 40.2Moz AgEq.

This follows a comprehensive re-evaluation of the Twin Hills, Mt Gunyan and Silver Spur deposits, including relogging of historical drilling, 3D structural modelling, historical mining void modelling and metallurgical test work.

Compelling targets

And there’s more. Thomson Resources’ (ASX:TMZ) new geological deposit models and metallurgical test work have also highlighted a number of ‘compelling’ drill targets at the underexplored Texas District that could represent extensions of known mineralisation.

This is a crucial step forward in the company’s New England Fold Belt Hub and Spoke strategy that seeks to build a 100Moz AgEq resource that will feed a central processing facility.

“I appreciate this has taken time, but here we have produced 3 different Mineral Resource Estimates from differing types of databases,” executive chairman David Williams said.

He added, the company had combed through multi-millions of dollars of data accumulated by others and satisfied itself with what is there and what it shows.

“As a result, we now have a clear view on what robustly sits in each deposit, and more importantly, where the gains can be found.

“A clearer picture has emerged of where higher-grade resources are likely to be found and how we can best extract the value from them.”

Breaking down the silver resource

The Texas District inferred and indicated resource of 11.26 million tonnes grading 54g/t AgEq, or 16.2Moz of silver, 18,500t of zinc, 10,500t of lead and 600t of copper outstrips total historical silver production of 4.2Moz of silver along with small-scale, high-grade base metals production.

It consists of resources at:

Twin Hills – 10.3Moz AgEq grading 52g/t AgEq
Mt Gunyan – 5.9Moz AgEq grading 41g/t AgEq and
Silver Spur – 3.3Moz AgEq grading 156g/t AgEq

Easily accessible

Twin Hills is a sediment hosted, low-grade, silver-(gold) deposit with minor associated zinc, lead and copper where about 25% of the known sulphide deposit was extracted via the previous Twin Hills open pit and heap leach operation.

This left easily accessible outcropping silver-gold sulphide mineralisation in the pit floor – which makes for a wonderfully simple restart of mining operations.

Mt Gunyan and Silver Spur

Mt Gunyan is an undeveloped silver-gold-zinc-lead deposit that outcrops as a prominent hill 3km northeast of the Twin Hills pit.

Most of the deposit is strongly-to-partially oxidised with silver mineralisation starting from surface and continuing to depths of 150 m below surface and remains open below this depth.

Silver Spur is a structurally controlled silver-base metal deposit located 2 km southeast of the Twin Hills.

Underground mining carried out between 1892 and 1925 produced about 2.19Moz of silver at an average grade of 800g/t, 690t of zinc, 1,050t of lead and 990t of copper and by-product gold.

Potential to grow

Modelling suggests that Twin Hills is open at depth in several areas where step-out drilling could quickly expand the mineralisation.

This is most evident to the north where higher-grade mineralisation is open at relatively shallow depths and not drill tested below approximately 60 m from surface.

Higher-grade silver mineralisation is also open to depth under the core of the deposit where interpreted ‘feeder structures’ represent an attractive target for higher grade mineralisation.

Spurred on by high-grade silver-zinc

Meanwhile, mineralisation at Silver Spur remains under-drilled with the block model highlighting that the high-grade silver-zinc Stokes mineralisation is open to the north and is a priority drill target to potentially expand the resource size.

Additionally, while underground rock chip sampling of the drive walls from 1971 could not be validated for use in the resource calculations, it demonstrates the footprint of the higher-grade zinc and silver mineralisation extends outside of the current block model limits, representing another attractive drill target to expand the current resource size.

Near surface oxide mineralisation outlined by previous drilling at Silver Spur North represents another attractive area for further exploration.

Upcoming activity

Thomson will carry out geological re-evaluation and drill hole database validation at Webbs ahead of calculating a maiden resource for the high-grade silver base metal deposit.

A large geophysics program is also underway at the Texas District to identify targets for a planned second quarter drill program that will prioritise high-grade Silver Spur style targets.

Preparation is also ongoing for the metallurgical and process study for the centralised processing facility.

This article was developed in collaboration with Thomson Resources, 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.