The Heemskirk Tin Project lies in exploration licence EL18/2011, on the west coast of Tasmania (Figure 2). MinRex has now held its Heemskirk Tin Project since 2012 and has been successful in identifying a number of the old tin workings, dating from the 1870’s-1880’s, and has collected a total of 129 stream sediment concentrate samples, 99 rock chip samples and 78 soil samples, for a total of 306 samples, in a search for large low-grade, or smaller, high to medium-grade tin deposits (Figure 1).
An Extension of Term Application, to Mineral Resources Tasmania, seeking a one year extension to this licence was granted on the 30 April 2018 and thereby extends the term of EL18/2011 to the 2 April 2019.
The area contains numerous small old workings for tin, both alluvial and in basement granite, with minor tungsten, base metals and silver occurrences also.
MinRex Resources Limited considers that this large area of granitic terrain is prospective for the discovery of large low-grade tin deposits, concealed deposits and/or deposits of other granite-associated metals (Figure 2).
The Heemskirk tin field saw a brief, hectic period of activity in the 1870’s – 1880’s, with companies spending on equipment rather than ore development, miners and prospectors inconsistently identifying cassiterite and ultimately a lack of capital, remote location and high costs forcing the closure of the field.
Subsequent exploration of the area since the 1960’s has seen piecemeal stream and rock chip sampling, along with geological mapping, sampling of the main old workings, the completion of three diamond drill holes, and various airborne geophysical programs completed.
There has been no detailed sampling or field work completed in the area over this period.
While the entire area of EL18/2011 is underlain by the Heemskirk Granite there is little detail or certainty on the phases of granite intrusion, nature of the mineralised structures and detailed mineralogy of the deposits.
While underlain by granite, the bulk of the area is covered with a thin veneer of quartz-rich organic soil, probably mostly less than 1m thick, rendering exploration and prospecting for mineralisation difficult, stream valleys are infilled with deeper alluvial deposits and dense vegetation.
The presence of a widely dispersed blanket of alluvial tin in the drainages of the area also compounds the exploration complexity.
Work to date by MinRex in the Heemskirk Project area (EL18/2011) includes an initial literature review, assessment of previous exploration in the area, re-processing and analysis of the government airborne magnetic and radiometric geophysical data and five field sampling programs, each of up to three weeks duration, that have collected a total of 99 rock samples, 78 soil samples and 129 stream sediment concentrate samples.
In the recent period, two field exploration programs have been conducted, one in April-May 2016 and a second in February 2017. These programs collected 86 rock samples from the old workings, 50 stream sediment concentrate samples from creeks in the west and south of the licence and a total of 68 soil samples from the flanks of streams that had previously returned anomalous stream sediment results (Figure 3).
In 2017-2018, the work program has comprised a complete re-appraisal of the results from all of the previous programs and the development of a comprehensive plan for the next stage of exploration.
Exploration at Heemskirk from 2012-2017 has been primarily aimed at testing drainage systems with panned concentrate sampling, augmented by selected rock sampling at the known old workings.
The next stage of exploration will comprise stream sediment concentrate sampling in the northern portion of the licence area and further soil sampling in valleys where anomalous stream sediment concentrate sample results have been returned in 2012-2017.
Further rock sampling will also be undertaken in areas with old workings, trenches and favourable outcrops. Also, sample residues have been retained and it is possible that future analyses may include other granite-associated elements such as lithium, thorium, tantalite, columbite, zirconium, yttrium, dysprosium, scandium and other REE.