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Crater Gold Mining begins exploration program at A2 Polymetallic Project in Australia

Published 06 November 2017

Crater Gold Mining has commenced exploration program at A2 Polymetallic Project in Croydon, North West Queensland.


  • As previously reported, significant polymetallic mineralisation (Zn, Pb, Ag, Cu, Sn) has been discovered in deep drilling at the A2 Polymetallic Project, Croydon, NW Queensland.
  • All nine drill holes intersected massive sulphide veins up to 13m in downhole length containing up to 10.13% Zn, 642 g/t Ag, 0.63% Sn, 2.1% Pb and 0.57% Cu.
  • A soil sampling program has commenced on a 3.6 x 3.6 km grid covering the previously drilled holes (a zone of 1,250m long by 600m wide) and the entire aeromagnetic anomaly, most of which is currently untested.
  • Samples will be assayed by the SGH geochemical technique which has been successful at other prospects world-wide in being able to detect geochemical anomalism for metals from depths of up to 900 metres.
  • It is anticipated that the cost effective SGH soil sampling technique will delineate priority targets that will be tested by drilling after the wet season in the second quarter of 2018.


Spatiotemporal Geochemical Hydrocarbon (SGH) is a cost effective, a deep penetrating geochemical technique that involves the analysis of shallow surface soil samples to detect various buried mineralised targets, including among them polymetallic targets. The analysis involves the testing for the geochemical signature of specific hydrocarbons, measured in parts per trillion, which are present in surficial residues from the decomposition of bacteria and microbes that feed on the target commodity (i.e. zinc) during their life cycle. Specific classes of hydrocarbons are associated with the presence of certain minerals and are therefore useful in exploration work for delineating drilling targets.

3D-SGH interpretations can generate geochemical anomalies for ‘blind’ mineralisation for a range of commodities and can also predict depth to mineralisation for drill targeting. The best response appears to be for mineralization associated with high quantities of sulphides. This geochemistry works well as an exploration tool for copper, gold, nickel, base metals and silver mineralization.

SGH soil sampling at A2 is being undertaken on a 3.6m x 3.6km grid. This involves 19, 3.6 km N-S orientated lines, 200m apart. These lines are being sampled at 200m intervals for a total of 361 samples on a 1:1 pattern. Additional samples will be collected as duplicates (1 in 20) for laboratory analytical tracking. It is anticipated that the sampling will delineate priority targets that will be drill tested in the first half of next year after the wet season.

Necessary land access consultations have been completed and SGH soil sampling has commenced. Program completion is expected by late November, with results expected December or early 2018.


The A2 project is a 1.5km x 1.0km complex aeromagnetic feature, characterised by a small magnetically reversed circular low shrouded by a doughnut shaped high immediately to its north, east and west. Nine (9) diamond drill holes for a total of 4,400 metres have been drilled and have intersected laminated shale basement rocks under 115 metres of Mesozoic cover sediments. Vein style mineralization was intersected in the basement rocks intermittently all holes to end of hole depths of up to 536.6 metres, defining a large hydrothermal system at least 1250m long and 600m wide.

Details of drill hole locations and significant mineralised intersections as previously reported in ASX Announcements are shown. These results indicate that all nine holes intersected massive sulphide veining in up to 13m downhole lengths with values of Zn to 10.13%, Ag to 672 g/t, Sn to 0.69%, Pb to 2.1% and Cu to 0.57%.

Geological age dating indicates an age of Upper Proterozoic (560 Million Years) for the host rocks and an age of Permian (285-284 Million Years) for the mineralization. It is encouraging to note that the latter age is very similar to the age of many of the world’s major ore deposits.

Mineral zonation is evident with some holes displaying a dominant association of Zn-Ag-Sn with minor Cu-Pb and others displaying a dominant Zn-Cu association. The presence of tin (mainly cassiterite with some stannite) and the association with massive pyrrhotite draws a striking comparison with the large world class underground tin deposit previously mined at Renison in Tasmania. A granitic association is also suggested.


Anomaly A2 is located some 37 kilometres NNE of the Croydon township. Croydon is a wellestablished town, with good infrastructure including a sealed, mainly single lane highway, stretching 560 kilometres from Cairns, a 1520 metre long sealed airstrip and all town services, including accommodation. It is a very historic town, with many of the original buildings restored, including among other sites, the original police station, watch house, courthouse and school in the Historical Village developed by the local council. 

Source: Company Press Release