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GB_Amateur last won the day on July 10 2016

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About GB_Amateur

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    Silver Member

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  • Gender
  • Location:
    Southern Indiana
  • Interests:
    Any and all metal detecting; geology of gold
  • Gear Used:
    Fisher Gold Bug Pro, White's TDI/SPP, Minelab X-Terra 705, Fisher F75 Black

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  1. I think there are exceptions both ways. Part of that depends upon your definition of 'hot rock'. Negative hot rocks (also called 'cold rocks' by some) have ground phases higher than the quiescent ground phase. Postive hot rocks do the opposite. I have a couple very large (near bowling ball size with masses in the 9-13 kg range) positive hot rocks which are so conductive that they give a TiD of 40 with the discrimination circuit and a phase shift value of 0 in All Metal. One of these appears to have a very high concentration of graphite. The other, I don't know its composition. Also I've noticed that metallic conductive targets at the edge of detection in All Metal mode (and thus out of detection range on the discrimination side) can have phase shift values greater than 20. But I do think in the vast majority of cases your rules-of-thumb hold.
  2. Buy-it-now, used for $650 including shipping. I know nothing about this (don't know seller, etc.). Just found it while searching metal detector page on Ebay. Looks like it was listed late yesterday as a 3 day sale. I don't expect it to last that long. SOLD about 2 hours after I posted this. Hopefully someone here got it.
  3. Looks like you cleaned this up between photos. What were the steps you performed? Just brainstorming here, but I sometimes wonder how accurate these XRF measurements are. One interesting thing (IMO) is the 1.5% iron content. Looking at Wikipedia: I see that there is something called "manganese brass" which is very close in composition to what you have, except with manganese instead of iron. Manganese is the next door neighbor of iron in the periodic table, and that means its X-ray line energies are close to iron's. Could the XRF identification be incorrect and this is manganese brass?
  4. There might be, but it doesn't look like an official Garrett solution: You might have heard of this Steve guy. I'm sure he'll chime in.
  5. Jim, I found the following at Amazon. Are these the two? A Field Guide to Rocks and Minerals (Peterson Field Guides) 5th Edition Peterson First Guide to Rocks and Minerals (I think I reversed the order -- first one is 461 pages and 1.1 in thick; second is 128 pages and 0.3 in thick.)
  6. Link to another thread on this site -- linked to a YouTube video that shows custom tone ID options of the Alter 71.
  7. Here's a video by detectingMO that illustrates the customizable tone frequency selection options of the RUTUS Alter 71:
  8. John, did you see this thread? In particular on page 2, AussieMatt links to an exhaustive study done in Australia, both air tests and in-ground tests of about a dozen coils for the TDI. (This was done with one of the big-box TDI's.) Based on that I've since bought a (used) NuggetFinder Sadie and my early tests confirm it is great. I have data which I'm going to post there to add to / enhance what has been done, but mine so far are only in-air tests which everyone knows have their limitations.
  9. While in Arizona this past February I found two tiny non-ferrous pieces with the TDI/SPP and had to buy a new scale to weight them. I was hoping to be able to do a decent specific gravity (density) determination using Archimedes Principle but even the new scale couldn't do that very well. The masses were 0.047 g and 0.058 g and they looked like copper under my strongest magnifier. (On my 'to buy' list is a stereo reflecting microscope.) Getting off on a tangent (I'm good at that...), 'g' means grams just about everywhere in the world. I think grains are abbreviated gr. I found out that this new scale (1 milligram = 1 mg = 0.001 g precision) is difficult to use because just about anything will give a force in the milligram range. I had a chance to buy a Mettler Balance in an antique store with even higher precision (factor of 10 smaller) one time and balked. I think it was about $10! Been kicking myself since I got back into detecting. I took two coils on that trip -- 3"x6" prototype and 5"x9" Miner John folded mono. I know I found one of the pieces with the smaller coil. I thought I found the other with the MJ, but not sure about that. I also don't know the depth since in both cases I used my pick to loosen the soil and then scooped through the loose stuff until I found them. But I strongly doubt they were anything deeper than an inch. Still, your 0.003 g with the MXT has my pieces beat by an order of magnitude.
  10. There are a lot of varieties but I think this is the one: I don't know how to grade these. My guess is around 35 but an expert (one of the grading services) is the route to go with something this valuable.
  11. Here's a decent site that shows the path of totality overlaid on state maps. Note that Sweet Home, OR is in it. I propose White's branding a 'Solar Eclipse special edition detector' just for this occasion!
  12. A professional electronics tech (or even a good amateur garage variety ) could do that. My solution has been to put the receiver (in my case the Deteknix model) along with the excess cord in a shirt pocket with closing flap. But maybe your cord is longer (total length from headphone to 1/4 in jack on mine are ~32 in = 80 cm) or possibly you've stretched it out over time so as to not be dragging your detector through the rocks when you're digging. Appears from your thumbnail photo that you also like pockets with shirts. IMO you can't have too many pockets when out metal detecting.
  13. I bet Nevada Chris (Ralph) knows all of these and will respond. In the meantime, I looked up a couple on Wikipedia and have cut and pasted the parts meaningful to your post: "Aluminum oxide --Al2O3 -- is commonly called alumina. It occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire." "Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase."
  14. Here's a decent treatise at White's website:
  15. First off, welcome MontAmmie. Second, you don't sound like a 'newbie' to me. Third, IMO you are wise to take detector weight seriously. There's a reason Minelab sells a harness for use with its Pulse Induction (PI) units. Wonder how comfortable that would be on a hot Florida beach.... If I were you, I'd 1) hang onto the DFX. From all I've read it's still a capable detector and your familiarity with it has value. Might want to review ground balancing techniques -- Steve uses his in tough ground in Reno. 2) Don't under-rate buying used, for examples: Ebay, DetectorProspector (this site's) 'Recent Classified'. I've read other metal detector forums also have pages for members to buy/sell. Typically, not counting recent releases, the selling price for good used detectors is about 60% to 67% of new prices. 3) Last but maybe most important: prioritize your expected uses. For example, you mentioned the Gold Bug 2. From what I've read (a lot here) that is primarily for very small native gold. It's possibly the best detector ever made for small/tiny gold (still almost a quarter century after Dave Johnson designed it), but you wouldn't be using it for anything else. I just got finished with a purchase decision myself. I made an Excel spreadsheet and compared the features/capabilities, ergonomics, prices, etc. that I wanted for about a dozen candidate models. I read everything I could find (especially here but also on Treasurenet, Findmall, and Dankowski forums) and watched a bunch of YouTube videos. Having your priorities crystallized will help you narrow down the finalists. Pick one and have fun hunting with it! It's still dark here and I'm getting my gear together to start early and beat the summer heat today. Next best thing to metal detecting and making a nice find is metal detecting and not finding a damn thing! I'm an expert at the latter.