This is also worth another read of just to refresh memories of Satimola reserve. Notice they have a number of minerals present. Look how close to surface the Potash is as we'll and the grades of 15.5k2O are on the mid to high end. That's my understanding.
http://www.asx.com.au/asxpdf/20130904/pdf/42j50819n36mxf.pdf
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