I don't think Mexus negotiated any sweetheart deal. However, Sipi had to come into the deal with some assumptions. You wouldn't process 1 ton of material without expecting some minimum value of return. Mexus claimed assays of 4000 grams of Au, it turned out to be less than 60% of that amount.
From Sipi's perspective they went from thinking they'd see about $7-8k in gold sales to less than $4k. Maybe they baked that possibility into their pricing agreement.
I admit I don't have an understanding of the specifics of the electrowining process and the carbon filters used. My (probably incorrect) assumption was that 1 ton of material would have been in addition to the weight of the filter. The next shipment has allegedly .5 to more material. Is that extra half ton mostly carbon too?
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