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  1. Steve I made a point of posting to your forum versus others hoping that you might reply and reply you did!!! Thank you and to the others that replied as well. The more a learn about metal detector technology and trying to use that technology to solve a problem the more I am amazed out how technical it is. When I knew nothing about metal detectors I thought all you had to do was swing the thing side to side until it beeped alerting you to a metallic item of interest. Was I ever ignorant. Before I started this thread I had never heard of a Falcon MD20 despite having put a good 100+ hours of research into this over the past few months. I have now bought a Falcon MD20. The Falcon MD20 comes with a business card that has been laminated with three things to it for you to play with. Pyrite, Gold (yes, a tiny spec of real gold) and little pile of black sand. This is what I experienced: Pyrite - silence no matter what you do. Gold - only makes sounds approaching it, never leaving it. Black sand - only makes sounds leaving it, never approaching it. The Falcon MD20 definitely makes noise with my auriferous rock. I'm calling it "noise" because my ears are virgin to metal detectors. I can't hear the difference yet between a zip, beep or a boing, I just hear noise or silence. The probe only makes noise approaching my auriferous rock, never leaving the rock (no matter what the acceleration or velocity of it leaving the rock). No matter what setting or anything I do, I cannot not get the MD20 to make any sound whatsoever as the probe moves away from my rock. The faster I approach the rock the louder it screams. Ground scanning: Just like everyone has said it is not a ground scanner. This needs to be almost touching the rocks for it to work and therefore you can't hover it over the ground. Hovering an inch off the ground makes this useless but it is not useless because it wasn't designed for that. I bought the pole mount for it (just some white PVC pipe) so I can walk around and poke/touch rocks with it. You often can't swing the probe over your target rock because there is no space to do so (i.e. branches, other rocks, crevice, etc.). I found a poking/stabbing motion worked best because you can always do that. From a distance I must look like a blind person lost in a rock field with my white walking cane. I have never used a metal detector but this no doubt is a much slower process than swinging a "normal" metal detector designed to scan the ground quickly and to some depth. However I can poke it into tight areas a search coil can't fit. Now my confusion with hot and cold rocks and how that relates to my Falcon MD20 and my quest for Auriferous rocks. Bear in mind as you read this that I have zero experience with "normal" ground scanning metal detectors and about 8 hours now with my Falcon MD20. I find I get only one of three results. No sound, sound when the probe is approaching the object or sound when the probe is moving away from the object. I tried experimenting with ways to get sound while both approaching and leaving and could not. The sound seems to be mutually exclusive to either approaching or leaving the object, never both. I have experimented with all kinds of metals and they all give the exact same result: sound when approaching, never when leaving. So I am confused then as to how the black sand on their sample card causes the opposite result. To me black sand is metal and should therefore I would expect the same result I get with metal, sound when approaching and not leaving. I watched a bunch of Youtube videos about this Falcon MD20 and a few of the video mention that this detector discriminates, non-ferrous sounds when approaching and ferrous when leaving, however that is not what I experience at all with the exception of the black sand sample. I am confused. Without understanding what is really happening my current guess is that sound you get when pulling the probe away from an object is from a semi-conductive material, but then I would think pyrite would make a sound and it is silent. I am still trying to wrap my head around what cold and hot rocks are and from what Steve is trying to explain to me sounds very similar to what I am experiencing with the probe only making sound when approaching or leaving an object but not sound in both directions, ever. Does hot and cold rocks have any relation to what I am experiencing? Steve, you mention the "old Tesoro Diablo uMax" that had two ground balance settings. If you balance out the overall ground and rocks that only make sound when leaving them, you would be left with only getting sound on approaching a rock, which therefore has solid metal in it of some kind.? If a metal detector responds to both conductive and/or magnetics does that mean you could detect a ceramic magnet (ceramic can't conduct)? Would my Falcon MD20 make as sound approaching or leaving the ceramic magnet? I'm guessing leaving? Auriferous
  2. Auriferous: In my case contains 20388 grams/ton Au (20.4kg/ton) Introduction: I found a single extremely high grade gold rock specimen and I am unable to locate more. Lode and Placer mining equipment would not find these other than a lode process crushing everything in the area. Specimens at these grades are worth more than the gold they contain. I do not own a metal detector but have spent a good hundred hours learning what I can about the technology and systems. Cold Rock: I believe I need a metal detector system that is optimized to locate cold rocks (non-ferrous negative hot rocks, opposite to ferrous hot rocks). I cannot obtain a resistance reading with a multimeter that is capable of reading millions of ohms even though the gold concentration is extremely high in both the assay results and with the naked eye. To me this means it cannot be metal detected as a solid metal object (nugget) of any size. However it might hopefully be detected as a cold rock of some size. Ground Conditions: Dry and no salt. Size: Shale (loose rock) slope with a little vegetation on top of it. The size of the rocks are mostly 2 inches to 12 inches with a few larger rocks going up to about 4 feet. There is very little "gravel" size rocks (under 3/4in). This specimen is about the size of a baseball (3in/75mm diameter) that I cut in half. The other half went to the assay lab (had I known I would have sent a MUCH smaller sample size). This half of the specimen weighs 146grams. The other half that got fire assayed weighed 180grams. So the original specimen before I cut it in half weighed at least 326grams. Mineralization: The location contains very little mineralization (as in very little iron). The only sign of "iron" is decaying/oxidizing pyrite. Some of the rocks have a lot of pyrite in them. I suspect some of the "pyrite" is arsenic based (Arsenopyrite) but I have not had an assay on those to confirm. Even some of the Au found in this specimen may be rare gold pyrite (Aurostibite). Trash: There is very little "trash" (as in manmade metal objects). I would even go so far as to say no trash whatsoever but I'm sure there is something in there. Certainly no aluminum wrappers that have been shredded thru a lawn mower. ASSAY RESULTS: Au = 20388.2 gm/t Ag = >100 ppm Mo = 23 ppm Cu = 435 ppm Pb = 1471 ppm Zn = 1032 ppm Mn = 1446 ppm As = 34 ppm Sr = 89 ppm Cd = 9.2 ppm Sb = 39 ppm Bi = 891 ppm Fe = 5.57% S = 5.79% What Metal Detector system to use for Auriferous rocks (cold rocks)? If I had not made this post to get feedback, my research/learning points me to purchasing a IB/VLF system like the White's GMT with a few different search coils for the first 12 inches of depth. However I do not feel confident in that decision because maybe it should be a Fisher Gold Bug Pro instead, or something else. Can a deep large object metal detector (relics) work for detecting "large" cold rocks like this beyond a few feet of depth in the ground conditions described above? High rez pictures of this specimen that I need to find more of are attached!
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