Hoov as always thanks for your level headed and informative posts.

Your observation that 1/20th of the material passes through 3/4" as compared with 2" screens is quite interesting. As one would expect with a smaller screen the grades should increase substantially. Is there a graph showing what this means quantitatively as one goes from perhaps 2" to a very fine grind? In other words, what does 'substantially' mean.

Although you might not remember we have privately communicated last year. A group with whom I work have an innovative device that for a reasonable cost might be able to bulk sample all the free gold quite accurately. Let me know if you are interested and I'll connect you.