Amigo, maybe the difference between the "Head Grade" and the...

Amigo, maybe the difference between the "Head Grade" and the "Calculated Head Grade" occurs because of statistical variations. That is, when the ore is first added to the leap leech pad, a number of samples are collected and assayed for gold. The average value of these assays is the estimated "Head Grade". After about 2 weeks or more of leeching with cyanide, most of the gold has dissolved into the cyanide solution. This solution is reacted with zinc or activated carbon to negate the cyanide from the gold. Then after some further processing, the weight of gold that was leeched can be accurately measured (because it can be processed into ingots). The remnant gold that wasn't leeched can be estimated by sampling and assaying the heap. As a result of these measurements, the company can use the weight of gold in the ingots and the remnant gold in the heap, to back calculate a more accurate value for the head grade in the beginning (ie the Calculated Head Grade). In the end, whatever the company presents as the Calculated Head Grade is the most accurate. The important point for us investors is that your table shows that the heap leech process appears to work well for the ore at Van Uden. As a result, I reckon that the company may be considering heap leeching of ore at the Van Uden onsite. Then negate the cyanide before shipping the product for toll treatment. If they can do that, the quantity of material sent for toll treatment should be greatly reduced, and the material would be at a higher concentration than untreated ore. That could reduce costs for transport, and cost of dumping of the waste by the toll company. We wait to see what the company determines is best.