Reno Chris

A blasting cap crimped by teeth - a good way to blow your head off - you can still see the teeth marks.

Got there a bit after 2:30 pm and looked for you, but didn't see you.

Hope those 5 are just the first of many.

I was thinking the same thing, so I recently acquired a lead bar, 13.5 ounces troy, a troy pound and then some, and not owning any pound sized nuggets myself, I figure its the perfect stunt double for that really large nugget for testing the performance of the GPZ. Good for testing and experimentation. I am figuring extra deep is not for bullet sized targets, but for large brass belt buckle sized targets.

Rob - I also found similar issues with broad positive signals from Suaro and barrel cactus when I was recently in Arizona. Apparently it may be any larger succulents that cause the signal.

It is a rough approximation sort of thing, but the reality of the situation is actually much worse as we do not detect targets which are floating weightlessly in a vacuum. The minerals of the soil do react also with the magnetic field of the transmit coil absorbing some of the field energy going to the target, and then also absorbing energy as it goes from the target back to the receive coil. Unfortunately, gold is often found in mineralized areas. As a result, "signals in the receive coil which can be millions of times weaker than the signal in the transmit coil" Bruce Candy, Metal Detector Basics and Theory

I pulled a used cover off of one the other day and there was very little in it. Tape or something else would be a good precaution, but its not like the SDC coil cover which seems to let in all types of stuff if not sealed.

Radiant energy disperses into all three dimensions and so decreases in the cube of the distance. So it's the inverse distance cubed. since the.energy goes out both from the coil and then from the target back to the receive coil, the total energy loss in both directions is the distance times 10 to the 6th power, or a million times.

If you get an 18 gram button in a 30 gram assay ton sample, It has to be be something that makes up a large part of either the Flux or the concentrate. The Flux has a lot of lead, the cons appear to be largely sulfides. It has to be something where there is at least 18 grams of it in the Flux and sample mix being put in to the crucible. Try cutting it with a hacksaw. Pyrite is harder than the hacksaw blade, so if it's sulfides you won't make much progress sawing it.

I've been pinpointing with it in a manner more like a double D even where the target is a shallow double blip on each coil overlap. I figure it swinging side to side in one direction then turn 90 degrees and swing over it again to locate it in that direction,marking an X where I think it is.

It cannot be tungsten, the meting point of tungsten is more than a thousand degrees higher than the maximum an electric furnace can reach. The heating elements would melt before the tungsten. Sulfides come off next to gold on the shaker table. If you didn't get it fully roasted, add nails or plenty of some other reducing agent like flour or charcoal, its sulfides. Put it on an anvil and hit it harder with something heavier than a rock hammer. Its not a nugget that has specimen value. Try sawing it with a hack saw - sulfides will be really hard compared to metals. Sulfide matte does look like a metal. Roasting ores within a closed electric furnace does not allow enough oxygen to roast a concentrate that is mostly sulfides. Roasting is not a heating process, its a burning process. Just as things do not burn without oxygen, sulfides will not oxidize without oxygen. If you are using a book that tells you how to do an assay, look at testing high sulfide ores.

The parks will be fine. Peavine is full of trash and bullets being so close to town. Sorry, I can offer no secrets of Olinghouse.

The possibilities of what has gone wrong are so many in number that it is hard to say. Additionally, you've given so little information that I hardly even know where to start. I don't know what kind of assay procedures you are using so that's a big question mark. I don't know if you are using a full oven fusion or some sort of torch type shortcut assay. Your concentrates appear to be mostly sulfides and sulfides require a special different assay technique than your normal standard fire assay. Are you adding a bunch of nails to the assay mix? The addition of nails to high sulfide assays is quite standard for the industry. The nails react with the sulfur. Sulfides do melt and when they harden they form into a material that looks very much like a metal - even though it is not. Once melted, sulfides to not easily roast off because only the outer surface can react with any air. The other thing that goes with that is of course you need to get a lot of air to get any kind of roasting situation going. I don't know that you are fully going through the cupelation process. What you have may be an alloy of lead with a little silver to harden it up. What happens when you hit the mystery metal hard with a hammer? if you strike it hard and it's a melted sulfide, it will shatter. If it's some sort of metal it will mash down like lead. I guess all I can say is if you can give us some more information and answer some of my questions above I may be able to offer you some help.

There does seem to be some ground balance issues, and its hard to tell in the video exactly what is going on, but I wanted to make a comment on the issue overall. In the video the operator runs his GPZ coil as if it were a mono coil (which he probably used on his last Minelab PI). The construction of the DOD coil is that it is made to swing from side to side, not to be pushed forward in and out. A mono coil is symmetrical all the way around the edge and it makes no difference if one swings from side to side or forward and back or out of angle from upper left to lower right or vice versa. The doubled D and DOD coils are made to be swung from side to side, not forward and back or in some other direction. You will not get the best performance out of your DOD coil by pushing it forward and back as the operator did the video and problems with going over uneven and differentially mineralized ground will be made worse as the operator effectively demonstrates in the video. In the white paper just released by Bruce Candy, he makes a point that trying to design a coil for the ZVT technology was a bit difficult because of the inherent sensitivity to uneven ground and mineralization changes. The DOD called design was the answer to this problem, but it really does need to be swung from side to side, not in and out as if it were a mono coil. The DOD coil does behave a bit differently than the coil's most operators have used in the past - it has a different geometry. You cannot just assume that it is exactly like all the coils (especially mono types) which you have used previously.

A company by the name of Depar has the distribution rights to sell Fisher metal detector products in Africa. You can do a Google search and find them and they can tell you about distributors they have in South Africa. The home offices for Depar are in Dubai and Istanbul. There used to be some very severe legal restrictions on gold prospecting in South Africa and I have no idea what the current state of the law is there. It may still be the same.

Contact your dealer and get a new battery. The CTX battery is good for about 4 hours operation on the GPZ. To not delay your trip, technically you could run the GPZ on the CTX battery in the morning, take an hour break for lunch and recharge the battery, then detect in the afternoon. Not really a great solution but better than nothing until you get a new battery.

http://golddetecting.4umer.net/t20867-detrackozi-gpz7000-covers

Try running the back light for the screen even in daytime - it makes the screen easier to see and use. The only screen protectors I have heard of are home made by cutting down a screen cover for a larger screened phone.

JP, you have thanked the folks at ML for their long efforts in bringing this detector to the market and indeed that is appropriate. However my friend, I would like to thank you for your very important part in making this complex new technology practical and easy to use for the every day prospector. It is no small effort and your voice is a most important one in the product development process. It is because of your passion for the best which can be achieved that there is within each ML detector a little bit of your good self intertwined and woven in. Thanks for doing all you do.

It worked for me both in Nevada and on our trip to California in just the same way.

The threshold is quite usable as it it when turned on, but give it a try and see how much more quiet the EMI adjustment makes the threshold. I only noticed this in the last couple of times I have had the GPZ out detecting - I did not see it before.

One thing that I have noticed, but can't really offer an explanation for is that running the EMI adjustment protocol every time the GPZ is turned on quiets the detector threshold quite a bit. In the past with my previous GP and GPX detectors, I would normally run that adjustment at the beginning of the day and then only afterward if I started hearing EMI noise. I have found that even if I just stop for a moment to talk to another detectorist, or take a short break for a snack or lunch, I really need to run the EMI protocol every time the GPZ gets turned on.

If your specimen has a solid slab of gold inside, it would respond as a solid piece the size of the slab. Given the size of the piece and the weight, it would seem there is some pretty solid gold inside. It does not appear to be much larger than the 18 gram specimen, yet is 5 times the total weight, and close to twice the total gold. The GPX does fine on that more solid, well connected type of gold. The mossy, poorly interconnected gold is what responds poorly on the GPX. Not all specimens are the same.

So I was out in the goldfields of California yesterday with Steve Herschbach and another friend who is a detector dealer. We did some quick tests comparing the 5000 and the GPZ on mossy, wiry gold that we had found previously. These were pieces from both Nevada and California. The smaller of the two nuggets shown in the attached photo weighs 3 grams and with an 11 inch mono set on maximum gain of 20, it was totally invisible to the 5000 - even when it was touching the coil. The detector made no response whatsoever. The GPZ on the other hand could see it at about 10 inches, and it was dug from a pounded patch that has seen many GPX detectors (including mine) at a depth of about 6 inches. The GPZ was set for difficult soil at only 12 sensitivity. So what is the performance improvement over the 5000 when one detector is blind to the piece and the other sees it at 10 inches? Mathematically speaking, it is an infinite improvement - a whole lot more than 40%. The larger of the two pieces pictured in this post weighs 18 grams and the 5000 could see it to a maximum of about 10 inches. The GPZ could see it at 20 inches, and it was dug with the GPZ at about 18 inches. Going from 10 inches to 20 inches is a 100% improvement - double the depth of detection and also a lot more than 40%. We also tested some specimen gold Steve had with similar results - the 5000 could not see the smaller specimens of a few grams size. Of course we all know that the 5000 performs very well with more solid nuggets and specimens. I have found lots of gold with my 5000, it is an excellent detector. However, the GPZ is a gigantic improvement over the 5000 when it comes to mossy, wiry, prickly, specimen and other similar forms of gold. Some may say there is not much of this type of gold out there. I would say in response, if most of us are using detectors that perform poorly on that type of gold, how does the fact that we don't find much prove that it doesn't exist? Truth is that there is loads of specimen gold out there and I think the GPZ will be finding a lot of it in the coming weeks and months. Geologically, many of the places where the nugget gold is truly deep are locations where the patch is sitting as a residual over a vein, and having a detector optimized for specimen gold would make very good sense. Some hard rock deposits tend to produce this type of gold. Smart prospectors with GPZ detectors will be using this knowledge to their best advantage. For me, I have been doing research to find places which produce this type of gold and I intend to be using the coming months to leverage this performance increase to the greatest extent.

I cant get on this forum to confirm and I am not willing to register, but supposedly this link: http://www.detectingwestaustraliangold.com/t5339-confirmed-12oz-1-1mt-with-a-gpz7000 is about a guy in WA who just picked up a 12 ounce nugget at 1.1 meters with a GPZ 7000. 1.1 meters is a little more than 3 and a half feet. Steve did you ever get registered for that forum? So consistent with the other thread, for those who don't want to be digging 3.5 foot deep holes, that is another reason why you may not want a GPZ. It just finds targets too dang deep.