Step out holes are not written in stone as to distance from the last hole. It depends on mineral, width of formation and other factors. In gold, narrow vein, it might be 25 metres, or perhaps 50. In coal it also depends, in deposit thickness, history of the deposit and deposit type as well. It is common to step out 500 metres. GXS has had bad luck with step outs and good luck with geophysically targetted holes so far. Their far flung holes are targetted, not step outs. I think their problem is they don't yet understand how to follow the geometry of the deposit yet. They said it could be range and basin, but it may run NE-SW or be complicated by folding, faulting or cross ridges. Who knows? All I know is some very close holes did not hit, leaving the conclusion that the coal seams run in another direction than originally surmised, or they are cut off occasionally by unusual topography conditions or ridges. What began to appear to me is that the coal lies in traps that are made of deep sink holes or valleys in the underlying Devonian surface and the thick seams are just here and there, perhaps 500 metres in diameter. This is just speculation of the loosest kind, so I cannot qualify its probability. I can't see why seismic which mapped the Devonian surface, or radar if it would penetrate that far would not develop the paleosurface to the extent where they could predict thickness. At any rate their geofizz is getting them luck in finding the outliers. Now they need a better followup method to delineate.
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