Review of Historical Soil Data Identifies Gold in Soil Anomalies around Yarbu Gold Project


  • Strong gold in soil geochemical anomalies identified around Yarbu Project
  • Anomalies overlie known mineralised structures and favourable host lithologies
  • Anomalies highlight complex structural settings within Yarbu
  • Minimal exploration undertaken over much of the Yarbu tenements
  • Field reconnaissance auger program to commence early May
  • Newly reprocessed historical geophysical data has highlighted previously unknown folding within TSC’s ground1


Twenty Seven Co. Limited (ASX: TSC) (“TSC” or “the Company”) is pleased to report that the collation and review of historical soil geochemistry, coupled with the reprocessing of open file historical geophysical surveys1, has confirmed the presence of favourable structural settings at TSC’s 100%-owned Yarbu Gold Project (“Yarbu”) which warrant first-pass exploration investigation.

As part of the ongoing exploration of Yarbu, the Company’s geologists have spent several weeks digitizing historical geochemical sampling and drilling undertaken by previous exploration companies across the Yarbu tenement package and surrounding areas.  Historical data has been obtained in this regard through the Western Australian Department of Mines, Industry Regulation and Safety (DMIRS) WAMEX Mineral Exploration Reporting website.

Significant regional historical gold (Au) in soil geochemistry as well as associated Arsenic (As), and Lead (Pb) corresponds to gold mineralisation identified in historical drilling, suggesting Yarbu could contain multiple structural gold targets that have never been tested by modern geochemical techniques.

Much of the surrounding tenure around TSC’s Yarbu tenements has undergone surface geochemical sampling; in particular by Beacon Minerals, Polaris Metals and Savage Australian Exploration who completed several large-scale regional soil grids over much of the Western Marda-Diemals Greenstone Belt which TSC has spent the past two months compiling into a regional geochemical database.  The geochemical sampling has been completed at various grid spacings and is dominated by auger sampling, with selected areas using sieved soils and is shown in Figure 2, 3 and 4.

The gold in soil anomalies identified at Yarbu appear to be associated predominantly with fold hinges along and proximal to the Clampton fault, which is a major regional crustal scale mantle tapping fault separating the Marda-Diemals Greenstone belt to the east and the large Yilgarn granites to the west.

Figure 1: Yarbu Gold Project tenement locations


Figure 2: Yarbu Gold Project showing current tenements and
historical geochem sampling coloured by gold ppb


Figure 3: Yarbu Gold Project showing current tenements and
historical geochem sampling coloured by Arsenic ppm


Figure 4: Yarbu Gold Project showing current tenements and
historical geochem sampling coloured by lead ppm


Figure 5: Map showing RTP_tile_Eshade magnetics under historical geochemical samples coloured by gold_ppb.  Also shown as pink lines are the interpreted folds over the central tenement which are potential trap sites for gold mineralisation.  The cluster of Geochemical samples, which shows elevated gold to the west of the tenements, reflects small but high grade gold occurrences.


Ongoing Exploration and Next Steps

Compiling all of the historical soil data into a single database has given the TSC geological team an unparalleled insight into the geochemical signature of known mineralisation around the Company’s Yarbu tenements.  Known mineralisation/prospects on the western side of the Marda-Diemals Greenstone Belt are Andromeda, Diemals, and Clampton (which are not on TSC’s tenure), which have shown that mineralisation appears to be present along and adjacent to the major regionally-significant Clampton fault and within fold hinges.  The historical soils also show the deposits that have been drilled historically – these show highly anomalous gold, arsenic and lead in soils above and adjacent to the drilled mineralisation.

A large first-pass regional auger geochemical sampling program is being planned for early May 2021, will be conducted over the Company’s 3 exploration leases at Yarbu and is designed to identify any precious metal, as well as arsenic or lead, anomalisms (Figure 6).

This auger program represents the first systematic exploration undertaken over Yarbu.  The program is expected to comprise around 660 holes.  The holes will be drilled on an 800m x 400m pattern.  The average hole depth is planned for around 1-3m depending on penetration rates, to allow for collection of a bedrock sample to analyze for gold as well as a full multi element suite.

Previously, historical auger drilling within the greater Marda-Diemals Greenstone belt has been very effective in identifying zones of bedrock gold, arsenic, and lead mineralisation under shallow soil cover.  For example, the delineation of a zone of bedrock gold, arsenic, and lead auger anomaly (>50 ppb gold, 100ppm arsenic, and 30ppm lead) extending for 1,300m x 400m beneath approximately 0.5-1m of cover, appears to correspond with the Andromeda Project.


Figure 6: Planned auger points over the top of RTP_TILT_NE shade


Figure 7: Planned geochemical points



  1. Historical geophysical surveys consisted of the following:
  • A subset of the GSWA 20m Mag merge
  • 1997 Johnson Range 100m MAG/RAD/DEM survey completed by Tesla Airborne
  • 1996 Barlee-Jackson Geoscience Australia 400m MAG/RAD/DEM survey completed by Kevron Geophysics.



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