New Zealand Gold Prospecting & Metal Detecting Forums Archive

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Discriminate trash metal in rivers - whats your experience?

chchnuggetdetect		Posted : Monday, 20 May 2013 12:07:02 AM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 5/05/2013(UTC) Posts: 63 Location: christchurch Thanks: 33 times Was thanked: 4 time(s) in 4 post(s)		I have done a few weeks worth of gold nugget hunting in various West Coast rivers and creeks. Most have so much scrap in them from axe heads, tiny sub gram nails, and all sizes of sluice pipe pieces, that if you dig every signal you'd never have time to find any gold. What brand detector are you guys using in west coast rivers, how reliable is it for discriminating iron from gold? Does your VLF pick up an annoying ammount of rocks?

goldstalker		Posted : Monday, 20 May 2013 1:22:38 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 11/10/2012(UTC) Posts: 454 Location: greymouth, west coast Thanks: 6 times Was thanked: 67 time(s) in 57 post(s)		hot rocks suck on the coast and there are alot of old junk in rivers as most have been worked from old timers even modern day miners. so my thought for you would be walk further into places bush bash alot. im just using a AT pro standard big DD coil i dont really seem to hit any rocks with mine i like the target id meter also and the depth gauge on the screen even a minelab x terra 705 would be good as it also has a screen and they find gold. also my AT pro has a iron audio button and gives a low tone iron sound instead of a mid range gold tone sound and visual number around 50 on my machine give or take 5 and also depends on depth but i can tell if my target is steel or has steel in it before i dig thats the main difference between VLF and a PI. ive found 2 tiny pieces of gold with mine. but ive been obsessed with coin and relic hunting lately :) Edited by user Monday, 20 May 2013 1:32:20 AM(UTC) \| Reason: Not specified

chchnuggetdetect		Posted : Monday, 20 May 2013 1:34:14 AM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 5/05/2013(UTC) Posts: 63 Location: christchurch Thanks: 33 times Was thanked: 4 time(s) in 4 post(s)		Thats interesting to hear you've found gold with AT Pro which is a general detector? I tried an ACE150 but its standard coil is concentric and picked up too many rocks compared to my PI. I think i'll try it again now. I have bush bashed and found metal in far places. I am interested in finding some schist which i don't think Ive seen yet

rgmcbrid		Posted : Monday, 20 May 2013 9:33:31 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 3/06/2010(UTC) Posts: 583 Location: Southland Thanks: 23 times Was thanked: 180 time(s) in 140 post(s)		I have not done a whole lot of detecting for gold, but enough to get things sorted out with my detector (Fisher F75). What I have found is that in 'all metal mode' if I get a strong signal and a low number, it is iron. If I get a weak signal that is a medium low number, that is usually small gold or lead. I assume a strong signal with a high number would be a big chunk of gold, but have not been able to verify this. As far as hot rocks go, they just sound different and I don't usually get fooled. If they get real annoying sometimes I will ground balance on a hot spot which gets rid of them or makes them sound really different, but does not seem to affect the gold/lead signals.
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greentater		Posted : Monday, 20 May 2013 9:49:18 AM(UTC)
Rank: Gold Dust Groups: Registered Joined: 29/03/2013(UTC) Posts: 5 Location: Waihi Was thanked: 2 time(s) in 2 post(s)		I am using a GPX5000 and having similar problems. Having said that it does have an iron reject function that can be utilised. I have tried this and essentially it starts to make a tone and then just goes silent, this tells you by default that you are over a non target species. I was told never to utilise this function when looking for gold as it will decrease the sensitivity of the machine. As a consequence every outing in Aussie resulted in a mountain of bullets, nails, staples, hob nails and with any luck a bit of gold. So far here at home I have just assembled the piles of scrap and no gold to date.

simon		Posted : Monday, 20 May 2013 10:39:08 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 7/01/2011(UTC) Posts: 789 Location: Central Otago Thanks: 33 times Was thanked: 239 time(s) in 150 post(s)		i've got a vlf detector. i dig all targets. it's a good way to get to know what is what metal wise and also paints a picture of what metal is about the area. it also shows you what metals in what size and depth will make each tone on your detector. i still think i have it figured but can get fooled every now and again thus the dig all targets mentality. i hate to think what gold i missed in my early days when i had faith in the metal discrimination mode. i've also got an extensive collection of bullets, nails etc. as far as finding no schist, that may be the problem. you need some bedrock as a starting point. find gold there and then try nearby shallow ground.
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Metal Kiwi		Posted : Monday, 20 May 2013 10:44:47 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 19/06/2011(UTC) Posts: 1,210 Location: Auckland Thanks: 498 times Was thanked: 484 time(s) in 322 post(s)		Originally Posted by: greentater I am using a GPX5000 and having similar problems. Having said that it does have an iron reject function that can be utilised. I have tried this and essentially it starts to make a tone and then just goes silent, this tells you by default that you are over a non target species. I was told never to utilise this function when looking for gold as it will decrease the sensitivity of the machine. As a consequence every outing in Aussie resulted in a mountain of bullets, nails, staples, hob nails and with any luck a bit of gold. So far here at home I have just assembled the piles of scrap and no gold to date. Interesting comment Greentater. I reckon it might be a good idea to try the iron reject function and see if it lets you hear past the junk and pick up on the gold more easily. I would be surprised if the sensitivity would be reduced much if at all as the iron reject should just focus the electronics more. Hopefully other GPX users can add more on this. MK
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rgmcbrid		Posted : Monday, 20 May 2013 11:04:25 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 3/06/2010(UTC) Posts: 583 Location: Southland Thanks: 23 times Was thanked: 180 time(s) in 140 post(s)		Quote: Interesting comment Greentater. I reckon it might be a good idea to try the iron reject function and see if it lets you hear past the junk and pick up on the gold more easily. I would be surprised if the sensitivity would be reduced much if at all as the iron reject should just focus the electronics more. Hopefully other GPX users can add more on this. I know pretty much nothing about PI machines, but believe it to be a general rule with VLF machines that discrimination causes a fairly significant loss of sensitivity. Not so much that you would notice hunting coins, but enough that you would miss a lot of little gold.
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5AMP		Posted : Monday, 20 May 2013 5:21:32 PM(UTC)
Rank: Gold Nugget Medals: Groups: Registered Joined: 3/11/2011(UTC) Posts: 57 Location: wellington Thanks: 105 times Was thanked: 16 time(s) in 11 post(s)		Please can you tell me if the GoldBug is likely to produce similar signals to your F75?

Metal Kiwi		Posted : Monday, 20 May 2013 6:37:46 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 19/06/2011(UTC) Posts: 1,210 Location: Auckland Thanks: 498 times Was thanked: 484 time(s) in 322 post(s)		Originally Posted by: greentater I am using a GPX5000 and having similar problems. Having said that it does have an iron reject function that can be utilised. I have tried this and essentially it starts to make a tone and then just goes silent, this tells you by default that you are over a non target species. I was told never to utilise this function when looking for gold as it will decrease the sensitivity of the machine. As a consequence every outing in Aussie resulted in a mountain of bullets, nails, staples, hob nails and with any luck a bit of gold. So far here at home I have just assembled the piles of scrap and no gold to date. Have you checked out the Minelab site Greentater? Here is a link to the GPX5000 page http://www.minelab.com/a.../gold-detectors/gpx-5000 Although I have not used a GPX5000 (I wish) I think you could be reducing the amount of iron you are finding and getting more gold if it is there. Hope the link provides some idea's for you. Chris MK
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rgmcbrid		Posted : Tuesday, 21 May 2013 1:15:03 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 3/06/2010(UTC) Posts: 583 Location: Southland Thanks: 23 times Was thanked: 180 time(s) in 140 post(s)		5AMP, I am not sure, I have only been gold hunting a couple of times with a Gold Bug and that was a while ago... if I stop playing on the internet and get some work done I will take one out this afternoon and play with it a bit and see what I think.
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greentater		Posted : Tuesday, 21 May 2013 4:16:00 PM(UTC)
Rank: Gold Dust Groups: Registered Joined: 29/03/2013(UTC) Posts: 5 Location: Waihi Was thanked: 2 time(s) in 2 post(s)		Originally Posted by: Metal Kiwi Originally Posted by: greentater I am using a GPX5000 and having similar problems. Having said that it does have an iron reject function that can be utilised. I have tried this and essentially it starts to make a tone and then just goes silent, this tells you by default that you are over a non target species. I was told never to utilise this function when looking for gold as it will decrease the sensitivity of the machine. As a consequence every outing in Aussie resulted in a mountain of bullets, nails, staples, hob nails and with any luck a bit of gold. So far here at home I have just assembled the piles of scrap and no gold to date. Have you checked out the Minelab site Greentater? Here is a link to the GPX5000 page http://www.minelab.com/a.../gold-detectors/gpx-5000 Although I have not used a GPX5000 (I wish) I think you could be reducing the amount of iron you are finding and getting more gold if it is there. Hope the link provides some idea's for you. Chris MK Thank you for that. I had actually sat down and watched a few u tube videos again yesterday afternoon and the machine was much more settled this morning. I am a little too used to cranking everything up to maximum gain in arid Australia. There is a wee beach just around the corner from home ideal for experimenting on however it is knee deep in trash (i.e. everything that isn't a gold or silver ring or piece of jewellery) however it is helping me get to know the gadget a bit better