Ann: Initial metallurgical tests Generate Positive Results, page-340

I agree with what BF says.
There is mineral SG, and there is particle SG. The particle SG is the combination of the SG of the minerals in the particle. BF is correct that usually finer grinding will liberate minerals from a particle and allow it to report to heavy or light fraction. This problem also occurs with optical sorting. Consequentially finer particles means more crushing and grinding. More energy! More COST. More water handling and treatment. More COST!
So... OPTIMUM particle size is the go, and a full understanding of the mineralogy is CRITICAL.

There will be SG difference with weathered and fresh YES. Is weathered and fresh different to process..YES. Is weathered and fresh have a difference in recoveries...YES YES YES.

I have no shares, this is an informed response to assist.