Resource estimations will use a top-cut to minimize the effect (weighting) of localized very high-grades. Usually ~ 1 opt, but I've seen 2 and even 3 opt used in some deposits. Depends on the statistics.
The old adage when dealing with super high-grade systems is to drill for location & mine for grade.
I visited an UG gold mine in Aus where drill holes commonly returned 1,000-3,000 g/t Au over 20-30cm. They'd map out the position and extents of the high grade vein with drilling just to plan the drifts for mining. They didn't bother doing a resource determination from the drilling (other than for a rough idea of what a stope might yield), but just calculated the grade from the tons mined and ounces that came out in the plant after the fact. They didn't bother with reconciliations (of ounces estimated from drilling vs ounces produced), standard practice in mining.
These super high-grade freaks of nature tend to be small though. Like THE TANNAHILL!!!
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