New Zealand Gold Prospecting & Metal Detecting Forums Archive

Has any-one got any analytical rather than anecdotal evidence on gold loss (if any) through dry scalping out large boulders prior to screening or other processing of 'wash'.?
Every-one goes on about gold sticking to boulders but what's the real evidence of it being very much ? Cost vs reward !!!!!!
Cheers

I agree with Lammerlaw, as above. Also though if rocks are too big to lift you can use a scraper to scrape off the mud into pan or whatever.
As for anecdotal evidence I used to get a gram or 2 regularly from a worked out gully where the old timers had thrown their large rocks. The gold and mud that they had left on the rocks was washing off and running down the V shaped gully under the stacked rocks. I simply reached up and under the rocks as far as I could at the lowest point, and scraped the dirt into a bucket. I seldom found more than a pan-full of wash dirt, but got some surprisingly good size bits, up to just under a gram. NUGGY

Hmm bit of a head scratcher - above, not sure how the big rocks end up with less surface area than the smaller material...... Maybe as a percentage hmmm dunno

Another thing to consider, is that as the gold often travels with the larger rocks in moving water, and lies on, under, against gold more often, so therefore logically as they have more contact with gold they must be more likely to get gold stuck onto them.

NUGGY

This is all interesting guys but all anecdotal not a consequence of a detailed study. Add this to the mix ...lol
How this came up was related to discussing increasing the value throughput of a 5 foot gold screen (trommel) for an operator.
They currently dig and truck (150 meters) ALL material to the plant ,dump it ,pick it up put in the screen( damage-down time),
pick up tailing, load truck and take back to the pit.
Our view : dig ,dump on dry vibrating scalper, undersize -500mm loaded to truck, now 20% richer plant feed plus less plant damage(stoppages).
Big rocks would vibrate some of the gold off them plus rock pile could be hosed off on virgin ground before going to back fill.

In conclusion I believe there may be some minimal material left on the boulders but the added value of the plant feed and the greater availability of the gold plant greatly outweighs the value of any loss. Any arguments ?
Cheers