A Sun baker that gave no sound to an SDC 2300

G'day AU_Toe

Off topic? Not in the least, for your question is that on quartz or ironstone rock with the possibility of it containing gold.
When I say a good high frequency VLF for sniffing out tiny bits of "detectable" gold within its host rock or matrix, means just that, on or over certain types/size gold, invisible or almost invisible to a PI detector.
Now less the use of a "Gold Falcon MD 20 probe" (for the detection of very fine gold not detectable to a VLF or PI unit within host rock), there is no other hand held device that I know of, that can pick up fine, smaller than sand size gold particles in host rock.
My advice to you is that if you believe there's possible very fine or close to microscopic gold within some of the rocks you have within your possession, then the only thing left is to crush some of your rock specimens, via the use of hand held tools such that within a steel dolly pot & pestle, or put through a motorised rock crusher, in order to see what fine gold might exist within.

Kon.

that's the beer money Dave


cheers moredeep