Yes he said that the mineralisation is "full of pyrrhotite" and that its both conductive and magnetic and that both IP and detail ground magnetic surveys have already been completed.
Pyrrhotite is a weird mineral because its a non-stoichiometric compound. ie the proportions of its elemental composition cannot be represented by integers.
Its formula is given by Fe(1-x)S (x = 0 to 0.2). When x=0 you get FeS which is the rare iron rich end member mineral called troilite which is non-magnetic. I just read that troilite can be found on earth but is more commonly found in meteorites, particularly those originating from Mars and the Moon.
It's the iron deficiency which gives the pyrrhotite its weak magnetic (ferrimagnetic) property which varies depending on the concentration of iron deficiencies.
Seeing as M1 is made up of a number of near vertical shoots with limited lateral extent the magnetic effect of the pyrrhotite should in theory be able to be detected and should outline bulls eye type targets centred more or less over the top of the ore bodies, as long as the depth of oxidation is not too deep and the host rock and surrounding rocks don't have very strong magnetic susceptibilities.
There is no way of really knowing what the magnetic susceptibility of the host rock is because it's a strange rock called mylonite defined by the high degree of plastic deformation of its constituent mineral crystals and not by its actual mineralogy. That basically means it can be formed from various minerals. I don't know what those minerals are so can't say how magnetically susceptible they might be.
All they can do is basically do the survey and see if they get a meaningful response. The good thing is that they know where the ore is now so if they get a nice magnetic signature over the ore any similar undrilled signature might be another ore body.
As far as the IP survey goes pyrrhotite is conductive so it should also in theory give a chargeability response. I don't know the ins and outs of these IP surveys as they can get technical because there are a bunch of variations on the same theme but they are sometimes useful in detecting disseminated sulphides. In general the resistivity patterns are largely controlled by the porosity of the rock. Weathered rocks and sheared and fractured rocks with higher porosity have low resistivities. The art with these surveys are the interpretations. It's easy to collect the data but then you need a smart dude to tell you what it all means. I would have thought that a long striking system of sulphide disseminations would be easier to find than a more laterally confined deep system like M1.
Once again its a matter of doing the survey and seeing if you get chargeability responses that stand out and that can be correlated to the existing ore shoots and then looking for similar signatures away from the know deposits. What you are really wanting to see are nice coincident magnetic and chargeability anomalies.
I wonder whether they will release the results of those surveys in an announcement or keep the results in-house? Richard also mentioned about 10km of geochem anomalies that are yet to be properly tested as well. Esh
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