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Decided against the Garrett ATX. I just purchased a new Minelab GPX 4800 with the 11 inch DD and 18 inch mono coils from Rob at http://robsdetectors.com. I very highly recommend doing business with Rob. This was a very tough decision. I had favored the ATX's simplicity, waterproofing and excellent value/price. But after deeply considering everything Steve and Rob said (plus many other people's views and very deep google searches) I realized the GPX is a better investment and a better machine to learn and master. The GPX beats the ATX on weight, comfort, battery design, battery life, coil selection, aftermarket add-ons, fine tuning and has a nicer sounding audio tone. The ATX's audio tone has a distorted mosquito-like sound which bothered me. And I worried about the ATX's weight. Minelab produces a more polished product in many areas. The higher price is justified. Thank you Rob and Steve!!

Absolutely agree on the GPX5000 being the best on the market. I'm leaning towards buying both a Garrett ATX (with the 12" DD and 20" mono) and a Garrett AT Pro for now. A deep PI and a great discriminating VLF and both waterproof for about $3K. This seems good for two people working together. We can examine each other's targets.

Steve, thanks for the USGS link. The mine location data is probably more useful than the BLS claim data I've been working with. I will let you know how the GPR works. It can already detect pieces of aluminum foil. Still lots of work to do. Even my homemade PI detector could detect small pieces of aluminum. LipCa: even if a GPR was limited to targets weighing over a pound (which it wouldn't be), I could still mount it on a truck and survey tens of square miles per day. A suitable radar antenna can achieve a decent stand-off distance and possibly a 10 cm to a meter penetration through ground, depending on the ground type and frequency. A metal detector has a field strength that rapidly decays away from the coil. Enlarging a metal detector coil to achieve greater depth increases the necessary target size. Radar works by very different rules. Based on this video: the Garrett ATX appears to match or slightly outperform the GPX 5000. Is there anything wrong with this comparison? Looks like this was done with both detectors on default settings. Probably the GPX 5000 can be optimized by a skilled user. EDIT: Just found Steve's review here: http://www.detectorprospector.com/forum/topic/160-garrett-atx-vs-minelab-gpx-5000/ The ATX looks like a winner for me. I would indeed use the underwater capability.

Steve & LipCa, Thank you for the detector recommendations. Sounds like the GPX 5000 or its predecessors are the best detectors to invest one's time learning. Which predecessors of the GPX 5000 could best transfer learned-skill to the 5000? The 4000/4500? What about earlier models? You're both absolutely right. We basically have zero experience with metal detectors. But we're willing to spend time and money learning, hopefully with good detectors in a good location. I did become effective with several detectors as a child in the late 1980s for coin and relic hunting. And I bring decent experience in geospatial software, 3D sensing, signal processing and general RF work. Has anyone published a list of locations to hunt for nuggets? Maybe even a list of geographic coordinates? I can analyze that with DTED and BLM claim data, pick out some patterns and maybe narrow down the list. This GPR is for indirect detection. Characterize the mineral content and layering rather than find nuggets directly. Its also fully experimental (don't mind if it fails), and quite inexpensive (less than $2000 total investment so far). While GPR will have excellent ground penetration, the discrimination challenge will be much harder versus a metal detector. Smooth rocks and conductive minerals will have similar radar cross section. I have no doubt that modern metal detectors are impossible to beat for direct detection. Its possible GPR might be capable of direct detection and discrimination of nuggets. But that would require a contrast mechanism other than basic radar cross section.

My apologies in advance for asking so many questions in one post. Two of us in Alabama are planning to drive west in October or November to go prospecting / nugget shooting for the first time. We plan to devote a solid 2 to 4 weeks to learning to find nuggets and placer deposits. Priority will be on shooting nuggets with metal detectors and experimenting with ground penetrating radar. What locations or regions should we hit? Northern Nevada seems favored by various blogs and the BLM claim data. Which two or three detectors should we buy given about $3000 to put towards detectors? Would it be better to get three detectors (one as a spare) or put more money into two better detectors? Steve's guides are the best resource I've seen and suggest the following detectors: Fischer Gold Bug Pro White's MXT or GMT Minelab X-Terra 705 Used Minelab GP 3000/3500 or GPX 4000/4500 Is interference a concern because two of us will be operating simultaneously? Or should we plan to operate some distance away from each other? Thank you!!