detecting in (presumed) tertiary gravel tunnels in Costa Rica

[BillA]

Anyone have any experience in detecting tunnel faces for placer gold?

I live in the Osa Penisula of SW Costa Rica and there are areas here that have produced large amounts of placer gold. Other than working the streams and rivers, much success was also had by tunneling along the 'ancient' stream/river beds (strike and dip unrelated to current topology). Many of these workings are now abandoned and I have the 'opportunity' to take a detector through them, for a deal of course.
Also to participate in the extension of an existing mine tunnel (or is it a 25m prospect??).

I have a Minelab 4000 w/extras.
Anyone have experience with such?

For what its worth, no shoring is used - but many of the tunnels are 40+ yrs old w/o caving.

Bill

 

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[Hoser John]

You need to talk to BCR-Bill in Costa Rica-google Hotel Fenix and get in touch with him--good man, better miner and knows CR righteously-John

 

[nforest]

Anyone have any experience in detecting tunnel faces for placer gold?

I live in the Osa --deleted--ula of SW Costa Rica and there are areas here that have produced large amounts of placer gold. Other than working the streams and rivers, much success was also had by tunneling along the 'ancient' stream/river beds (strike and dip unrelated to current topology). Many of these workings are now abandoned and I have the 'opportunity' to take a detector through them, for a deal of course.
Also to participate in the extension of an existing mine tunnel (or is it a 25m prospect??).

I have a Minelab 4000 w/extras.
Anyone have experience with such?



For what its worth, no shoring is used - but many of the tunnels are 40+ yrs old w/o caving.

Bill

I have property and lots of family exactly where you are talking about. Don't get caught, its illegal to mine on most areas around the Osa. if someone is guiding you in, and telling you that its legal, they are most likely taking your money.

 

[BillA]

an update, 2 1/2 yrs later - lol

Visited a friend's property on the 'backside' of Corcovado Park who has a ridge riddled with various layers of conglomerate and tunnels, confusing stratigraphy (to me).
He works a tunnel some 250m in, ~ 1m/wk, the wk before some 45 gms, all nuggets ~1/2 gm to 8 gm, nuggets sold by weight only - no gringo buyers in sight (getting too violent I suspect).
GPX 4000 worked fine, detected a pair of 1 gm nuggets ~ 3" into the blue (black) clay pay zone, very abraded surface yet well rounded - in clay with a green/blue surface where not cleaned. These bits would have been found in any case as they were in the working face. Am not too enthused about detectors in mines, a ton of work to even access them after 20-40 yrs, and what can be concluded ?. But most interesting if exhausting hiking.

I am from Calif and the family ranch mined gold during the 1880s, but I am stupefied by the amt of gold all over the Osa. Of course it is "protected" now, but the gringos made a killing in the 1980s - exploration permits used to mine but they could not get to bedrock. Eat your heart out Bill.
And of course the mining has been going on for 1500 yrs, the evidence is all about and underfoot.