It really depends on what is controlling the mineralisation. It...

It really depends on what is controlling the mineralisation. It is fairly normal to see a greater dispersion of mineralisation in the supergene zone (weathered rock). This is largely due to hydrological affects of ground water rising and falling and migrating across the deposit.

It is also common to get higher grades in this zone as a result of concentration as erosion has taken place, particularly true for heavy elements like gold which are not very mobile.

I think in the interpretation of Luni in my previous post that there is a pretty abrupt boundary in the southern and western portion and a larger mineralised 'halo' to the north. My guess is that the carbonatite is a very strong control on mineralisation even in the weathered zone. It is pretty important that I point out that this is not a grade interpretation, its a metal-endowment interpretation, so thickness is as important a component as grade in the contours. I would really like to have more data to interpret structures based on grade.

The other thing is that the yellow zone includes material up to 19.9 %*m. Leaving aside met (which is a critical determinant for a resource estimation) I think that in a large deposit like this we might expect (hope) grades of 0.5% to be mineable. A 19.9 would equate to 40m @ 0.5% for example. Whilst I refer to it as "mineralised" there's a chance that a fair chunk of this material might be included in a resource.

I wouldn't be game to make any resource estimates at this juncture because metallurgy will be critical for lower cut determination and which will drive the grade and quantum of the resource. The JORC code makes it incumbent on the resource geologist not to include any material which doesn't have "reasonable prospects" for eventual economic extraction, that's why the metallurgy is so important.