Geology and Exploration

The Heemskirk Tin deposits are granite related cassiterite and basemetal stockwork and replacement style mineralisation hosted in older sediments and volcaniclastics of the Zeehan Sub Basin, Western Tasmania.  Mineralisation is generally stratabound. The stratabound mineralisation is structurally controlled on fold/fault dilation zones between lithologies of contrasting rheology.

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Schematic Geology Cross-Section Showing Queen Hill and Severn Tin Deposits

A total of 58 diamond drillholes (18,709m) have been completed by Stellar over the Heemskirk deposits since 2010. A further 133 historic diamond drillholes (31,485m) have been completed prior to 2010 by other companies over the Heemskirk deposits.

The Heemskirk Tin Project includes 4 deposits which have been defined over a total strike length of approximately 1,300m to depths of <500m below surface.

Orientation, Strike Length, Dip and Thickness of Heemskirk Tin Deposits

Mineralisation in all of the Heemskirk deposits remains open down plunge. Tin occurs principally as cassiterite with minor stannite and base-metal sulphides located towards the top and periphery of the Queen Hill and Montana Deposits.

Mineral Resource

An updated total mineral resource for the Heemskirk tin deposits of 6.6mt @ 1.1% Sn (70,930t of contained Sn) at a cut-off grade of 0.6% Sn has been defined in accordance with the JORC Code 2012 by technical consultant, Resource and Exploration Geology, in May 2019. There has been no material change to assumptions since the resource estimate was completed in 2019.

 

Heemskirk Tin Project Mineral Resource Statement (JORC 2012), May 2019

2.12 Mt of the Heemskirk total mineral resource is in the Indicated Mineral Resource Category and 4.48Mt is in the Inferred Mineral Resource Category.  All deposits have higher grade zones and are amenable to mining at higher cut-off grades. All deposits open at depth.

Heemskirk May 2019 Mineral Resource Model @ 0.6% Sn Cut-off Grade – Indicated Resources highlighted in Red with Inferred Resources in Green

Benchmarking the Heemskirk Tin Project Resource

Heemskirk is the highest grade undeveloped tin resource in Australia and the second highest grade undeveloped tin resource globally.

Comparison with Renison Tin Mine

The Renison Tin Mine located 18km to the NE of Heemskirk has similar geology and ore genesis to the Heemskirk Tin deposits.  Renison started with a 4.0Mt reserve and 5 year mine life in 1968 and has since increased the mine life to 50 years with at least another 15 years to go. The Heemskirk deposits contain only ~20% of contained tin found at Renison to date.

 

Comparison of Heemskirk and Renison Tin Deposits