Metal detectors

Submitted: Tuesday, Jun 25, 2013 at 06:36
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We are planning for our trip to Alice and wondering if it has been organized for anyone able to do a demo on how to use a metal detector (without the sales pitch) .
I did look back through the forum as I thought it was mentioned earlier but couldn't find anything on this
I would love to find out some info about metal /gold detecting and I am sure I am not alone.
cheers kev&chris
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Reply By: Uncle Buck - Tuesday, Jun 25, 2013 at 21:20

Tuesday, Jun 25, 2013 at 21:20
Kev & Chris
You’re not on your own with that request, it would certainly interest me as well. Although there is a tight schedule at the muster maybe it could be slipped in somewhere. Of course someone, or a few, would need to give up some of their close held secrets. May be they could tell us where to find it as well. I think that may be asking a bit too much.
Scott
AnswerID: 586036

Reply By: Grumblebum & Dragon - Wednesday, Jun 26, 2013 at 20:51

Wednesday, Jun 26, 2013 at 20:51
I did a metal detecting session at the 2010 Muster in Atherton - unfortunately we will be in Africa and cannot make Alice

For gold you really need to get a Pulse Induction detector and I strongly recomend Minelab. Buy the best you can afford at least an Extreme or above but more better a 4000, 4500 or 5000.

By and large VLF machines are a waste of time in the Goldfields due to the high levels of mineralisation - the machines just warble and you will find it difficult to pick a real signal.

Join one of the gold forums and ask questions. I will post more info when in a mobile area. Currently perched on the top of a hill in the vehicle and running out of battery.

cheers john
AnswerID: 586037

Follow Up By: Grumblebum & Dragon - Wednesday, Jun 26, 2013 at 21:14

Wednesday, Jun 26, 2013 at 21:14
http://golddetecting.4umer.net/ This is one of the best forums - lots of reading here. No cost to join, just register

Cheers John
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Reply By: Grumblebum & Dragon - Friday, Jun 28, 2013 at 00:50

Friday, Jun 28, 2013 at 00:50
Here are my 2010 notes I have just updated them.

Metal Detecting and Gold Prospecting

The Basics

Detectors
There are two types of detectors on the market VLF (Very Low Frequency) and PI (Pulse induction) machines. Both will find gold and of course all other metals, however each type have their specific advantages and disadvantages and it is important to understand these before rushing out and buying a detector - which is an expensive bit of gear. For Pulse induction Machines consider only Minelab machines – built in Australia for Australian mineralised condition. Minelab also make a range of very good VLF machines as do the American Whites range. Avoid the cheap Chinese crap marketed on eBay. If you want to buy a cheap machine for a ‘try’ consider a Garret A2B or ‘Groundhog’ they were the choice of the professional in the late 70s and 80s. They come up on eBay occasionally for $50 - $100.

VLF Machines
These detectors, which have a base technology that has been around since the 1970s, are today models which are very much more sophisticated than the early machines. These detectors have smart discrimination capabilities which means that they have the capability to differentiate between ferrous and non –ferrous metals. Generally the more expensive the model the better the ability to select or reject different metals and alloys. Why is this important? – it will save you hours of digging worthless junk.

These VLF machines have a couple of disadvantages for the gold prospector. Firstly they tend to get noisy in highly mineralised ground such as is found on many of our goldfields – but not all. This ‘noise’ (whistles, squeaks and groans) makes it hard to differentiate the genuine signals. They will handle moderate mineralisation when used by an experienced operator. Secondly depth, typically a VLF machine will detect down to 30 -35 cm depending on target size, shape and make-up. A PI or Pulse Induction machine will detect down to a maximum of about 90cm – again this is heavily dependent on size, shape and make-up.

In summary the VLF machines are very good discriminating detectors and ideally suited to detecting beaches, parks and recreational areas (current and old time) for artefacts, coins and jewellery. The beginner will probably find more gold in the form of jewellery on the beach than in the goldfields – plus plenty of money. When our kids were young I used to take a Garret Groundhog down to Broome beaches when we were on holiday. An hour or two would generate enough coinage to pay for the hire of our deck chairs and ‘boogie boards’ for the kids plus some ice creams. They can be used in the goldfields with a greater or lesser degree of success depending on your level of experience and the degree of mineralisation present. Remember in the 70’s and 80’s millions of ounces were found with VLF machines.

Pulse Induction Machines
These machines were first introduced about 12 years ago. Their significant advantage for the gold prospector was that they were much less affected by mineralisation compared to a VLF machine and they could punch down much deeper. However they only have very basic ferrous/non-ferrous discrimination capabilities. The general rule when gold prospecting is to always dig everything. For example sometimes gold is attached to quartz or ironstone, ironstone being highly mineralised can generate a signal. Ironstone with a small nugget attached could be rejected as ferrous.

The other significant disadvantage is cost. A top of the range Minelab 5000 will cost over $6500 and a couple of extra coils and other ‘nice to haves’ like a good pick, pin pointer and a GPS and you are up for the equivalent of 6-7 ounces of gold. However, as a hobbyist you don’t need to spend that sort of money.

The 4000, 4500 and 5000 Minelab model have digital menus which can be difficult to master for a newbie. Stick with the factory presets to start with. There are some good DVD out by Johnathon Porter that are well worth the money. Also read the manual and then read it again and keep it handy for quick references.

Machines like this can be set up to run mono coils in highly mineralised soils and detect specks down to 0.1 grams within a few inches from the surface – larger bits much deeper.

Coils
Not all coils are the same. There are three basic types of coils, Mono coils, DD coils and salt coils and they come in both round and elliptical shapes. A very good 4500 models can be bought for around $4000

Mono coils have a cone shaped detection pattern below the coil; this means that to get the maximum depth coverage you will require to have a good overlap on each swing – at least 50% Mono coils do not have the ability to use ferrous discrimination

DD coils have a blade like detection pattern that runs from the toe (front) of the coil to the back at full depth all the way. This obviously requires much less overlapping. So why not just use DD coils? Ferrous discrimination can be used with a DD coil. The pro’s dig virtually everything.

A DD coil will not punch quite as deep as a Mono coil and are generally less sensitive to small targets; however they are much better at handling heavy mineralisation than a mono coil. Mono coils are much more sensitive, detect a little deeper but generally don’t handle mineralisation well as mono coils – but skilled operators can overcome this quite easily. The the latest Minelab 4000 and 4500 and 5000 models are much better at utilising mono coils in mineralised ground.

Big coils detect deeper than small coils but are less sensitive to small gold. Small coils are dynamite on small and relatively shallow gold but won’t detect deep nuggets

Salt Coils are specialised coils only for use on salt pans – in WA quite a few of these pans hold gold.

How deep will a coil detect?
There is no definitive answer; depth is affected but the target size, shape or orientation and make-up. Small target can only be detected at shallower depths and a flat item will be ‘seen’ at a greater depth than a round or on-edge target of the same weight. A highly ferrous target will produce a better signal at depth than ‘specie’ or nugget included in ironstone or quartz. Ferrous targets produce a very sharp pitched response compared to a more mellow sound of gold.

What to buy?
I would recommend that before buying anything you should join a club if one is available or if your interests are primarily chasing gold then get booked onto a Gold Detecting Safari. Both will provide heaps of information and advice – a bit like joining the BOG. On the safaris you will get to use the latest Minelab PI machines and will be guided and mentored by very experienced professionals who will take you out to good country – often on private leases where you stand a good chance of finding some gold. After all, their business depends on happy customers and happy customers are the ones that find gold!

Then you can think about buying a machine. My advise for the beginner (after doing the above) would be to buy a good second hand machine from a reputable dealer who should offer good advise and a warranty on any machine sold. For gold, a Minelab Extreme or above would be the go. Ditch the old 6 volt dry cell battery (or keep it as a reserve) and buy a 12v Lithium Iron battery which can be regulated down to your desired voltage. (I used to run my 2200D at 7.3 volts compared to the factory 6 volts – gives a bit more sensitivity and depth – now use a 4500) These battery’s will run at the regulated voltage all day and some. The old dry cell batteries started to lose voltage soon after you switched them on and may only be running at 80% at the end of the day producing loss of depth and sensitivity. Most of these 12v batteries come with a built in signal booster which are great for bringing up those faint soft signals that usually indicate gold. They are made by Coiltek or by Reeds Prospecting in Perth who produce the Lucky Lark model – mine is over 5 years old and has never missed a beat. I think their construction is better than the Coiltek model

And finally buy modern lightweight coils, at least one DD and one Mono – the 11” round coils ( or similar sized elliptical coils are a good mix of depth and sensitivity. The best makes are Nugget Finder, Coiltek and Commander coils. (Minelab)

Once you have bought a machine – RTFM (Read the ‘effing’ manual) and read it again and again until you understand what it says – then go out and practise. If you still don’t get it – talk to your dealer, pose a question to a more experienced prospector or even try joining one of several gold prospecting forums on the web and ask a question there. (Avoid the Finders Forum, they are a mob of anal retentive d***heads more intent on dropping bleep on each other than helping newbies.)

How do you detect?
Step one make sure your machine is set up properly with all the straps on the harness well adjusted, bungy cord set correctly to balance the weight of the coil you are using. Don’t forget to take the required ancillary items – pick – magnet – water bottle etc. Are your machine settings correct? You need to set the ‘threshold’ (background hum) to a just audible level. Check to see the various switches are correctly set. If in doubt read the manual again!

Commence a slow even sweep, keeping the coil parallel to the ground and almost brushing the soil. Overlap your coil sweeps depending on what coil you are using. Listening to the signal is more important than looking – you need to concentrate. If you get tired take a break otherwise it will affect your detecting. Any signal spikes, how ever soft, that differ from the threshold tone sound should be investigated. I usually use my boot to scrape away the surface detritus and then check the signal again. If it is still there I will use the pick to scrape off the top couple of inches. The signal should improve in volume and clarity as you get closer to it. Try and ‘pin point’ the target as best you can – try sweeping slowly at 90 degrees carefully noting the position of the best response. When digging with the pick, dig around the target – not down on top of it. Many beautifully shaped nuggets have been spoiled from being hit with a pick.

Once the target is out of the hole – use the pick to divide the spoil pile in two and check to see which pile has the target. Continue to do this until you only have a smallish pile to sort. Use a good ‘rare earth’ magnet (enclosed in a plastic bottle) to check the final pile for magnetics, such as ‘old timer’ nails or tacks etc. The magnetics adhering to the plastic bottle can be simply removed by giving the bottle a vigorous shake – over an area you have already detected!

If there are no magnetics than grab a handful of the material and run it under your coil and if there is no signal discard it. Continue in this fashion until you unearth the target. Finally, recheck your hole and spoil pile before re-filling the hole. Always fill your holes.

Some people use a small plastic trowel instead of the hands for check for signals….. it’s easier on your hands and nails – less splinters and thorns etc.

I usually wander at random following good looking ground until I hit a nugget. Then a more intensive search is made to find its mates. If you pick up more than three or four bits – however small – in the same area it is worth ‘gridding’ – it could be the start of a ‘patch’. Gridding requires that you carefully cover the ground in a slow methodical search. Some people peg out tapes/string in a grid pattern but a more popular method is ‘chaining’. This requires a bit of medium weight chain (enough to make a mark when dragged over the ground) about a metre long dragging on the ground and attached to your belt by a length of cord. Having chained in one direction and overlapping your chain marks then do the same at 90 degrees to the original lines. Finally, if you were originally chaining by swinging a small coil, then change to a large coil and repeat the exercise – looking for larger deeper nuggets.

Where to Detect?
Recognised gold fields are a good starting point for beginners. Gold is to be found in every state of Australia. Goldfield maps are sold by every dealer – these can range of general state wide maps down to 1/100,000 scale maps (1cm =1 kilometre). Probably the most popular size are the 1/250,000 scale maps. General software maps such as Natmaps Premium Edition often show the locations of old and current mines. (Geosciences Aust. The government mapping service – cost about $100.00 for the whole of Oz on 1/250,000 scales). The internet is also a good source of research, try Googling “Gold mines around X place”)

Whilst I am not up to speed yet on areas other than WA, the mining regulations there allow you to prospect on any UCL (Unallocated Crown Land) not covered by mining or granted exploration licenses or leases. You can, with the resident pastoralist permission detect on any pastoral lease not covered as above. In some instances you can even access some exploration leases utilising a 20A permit which gives you access for 3 months. Always check with the relevant Mining Registrar in the region if unsure.

Often when looking at gold maps or geological maps you can often see the old mines following a definitive ‘line of strike’ where the old shafts or scrapes follow a distinctive line or direction. If you think the existing area may be heavily detected then try extending the line of strike and searching fresh ground at either end. Anyone that tells you “all the gold is gone” or it is “flogged out” just ignore.

Learn to read geological maps – they will provide heaps of useful information. They can be expensive at about $15.00 each but are available on the net for free if you know where to look.

What does good ground look like? Quartz and ironstone outcrops and the eroded or weathered outflow from these structures are worth a look. Often referred to a ‘pepper and salt country’ due to the intermixed dark ironstone and the light coloured quartz sometime grouped in patches. Obviously anywhere that has been scraped (surfaced) or is showing old workings such as shafts, costeans or dry blowing patches is worth careful examination. Old dry blowing patches are often identified by piles of fine material adjacent to piles or coarser gravel resulting from the sieving separation of the dry blowers. These piles may now be almost flattened out due to weathering action over the last 120 years. Be very careful about entering old shafts or tunnels – loose structures, weathered rock and bad air can quickly kill you – they often harbour snakes as well.

When going out in the bush to detect, even if there is two or more of you, always let someone know where you are going, when you plan on getting back and what action to take if you don’t get back in a reasonable time frame. You should take with you ample suppliers of water, a first aid kit, UHF radio - preferably 5 watts, map, snacks, matches, knife or multi-tool and a small hand held GPS such as the Garmin Etrex ($135.00).

Attitude is Important
You will not find gold if you are tired, dejected or bored. You need to stay fresh and alert to be able to concentrate. You need to take a bucket full of optimism and add a dash of luck. Take detecting as a great hobby when out in the bush or on a beach. It’s a healthy lifestyle and you get to see nature and the wildlife at its best. Finding gold is just a bonus.
John Mack © 2010 – the macks1@bigpond.com
AnswerID: 586038

Follow Up By: Uncle Buck - Friday, Jun 28, 2013 at 02:41

Friday, Jun 28, 2013 at 02:41
John
Many thanks for the information and such a comprehensive reply. That should keep me off the streets for a while but what a great document to start off from.
Scott.
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Follow Up By: Willie - Friday, Jul 05, 2013 at 17:36

Friday, Jul 05, 2013 at 17:36
Hi John,
Great info. great effort.
Just got back from a month detecting Ravensthorpe, Hatter Hill, Kurnalpie and Mt Monger. The first two weeks at Ravensthorpe and Hatters Hill were a disaster. Ended up scrounging around for the last 14 days for 29gm. Got home last night for a beautiful long shower.
Willie.
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FollowupID: 855184

Follow Up By: Col & Diane - Monday, Jul 08, 2013 at 07:53

Monday, Jul 08, 2013 at 07:53
You won't find a better more comprehensive and accurate introduction to detecting than that. Great post John.

Regards,

Col and Diane
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FollowupID: 855185

Reply By: aubs. - Monday, Jul 08, 2013 at 05:27

Monday, Jul 08, 2013 at 05:27
I have previously posted about trying to organize someone from ML to attend and as yet I haven't got a hold of the right ear.

However it not as much about the metal detector as about but where to look. If you are passing through Calliope Cross roads, just outside of Gladstone Qld, send me a message or email me aunuggets@bigpond.com I will do my best to spend a day or 2 with you and cover very basic gold prospecting and coin and treasure detecting. Look for my threads on the BT site.

I will not be able to attend the Alice meet or I would have been doing demos there for anyone interested.



AnswerID: 586039

Reply By: Willie - Monday, Jul 15, 2013 at 08:56

Monday, Jul 15, 2013 at 08:56
Four weeks in June, on the goldfields of Western Australia.

Post Jigalong on Thu Jul 11, 2013 6:49 pm
.
Four weeks in June, on the goldfields of Western Australia.
We arrived in Norseman on June 1, armed with a heap of 40Es for ELs in places we had never detected before.
“Haggis” my Scots mate had come from Perth and I had towed my 16’ van over from Sydney in 4 days. Normally we both just go on a couple of GPA Tours every year, but this year, we were on our own.
It was to be an exploration of areas, as well as a search for nuggets. We had 40Es for four areas :
• Kundip , south of Ravensthorpe – 3 days detecting.
• Hatter Hill, North of Ravensthorpe - 2 days detecting.
• Kurnalpie, ENE of Kalgoorlie 4 days detecting.
• Mt Monger, ESE of Kalgoorlie – 15 days detecting.

Kundip
I had read in G & G about nuggets being found in this area and as I had heard hardly a mention of it on the forums, decided we should explore it. When we drove in, we immediately understood why it had received so little attention from detectorists. The thick, low scrub, made it impossible to detect in the natural bush. It was only possible on the tracks and in the clearings where camps had been – both areas were covered in junk though.
We did manage to scrounge a few nuggets out of one of the creeks that we battled our way into, but even though there was gold mines thick on the ground (gold not copper), I would not recommend Kundip to anyone, unless there had been a bushfire through there.

We headed off North to Hatter Hill on a good dirt road.



Hatter Hill
Once again, we had read in G & G about nuggets being found at Hatter Hill and I had never even heard a whisper about the place on any forum. There is a half dozen mines in a triangle spreading south from the open cut on the actual Hatter Hill and our 40E covered a number of them.
We camped at one mine in the south of our 40E, which was a collection of small, shallow open cuts with so much quartz surrounding them it looked like snow had fallen. We could find no gold there - either out wide or on the piles. There was bugger all detector holes either. After two days of sightseeing at Hatter Hill, we left and headed north for Kalgoorlie via the Western Areas nickel mine Cosmic Boy.
I think if you had a lot of time to explore Hatter Hill, there could be some rich rewards.


Kurnalpie
We had a 40E that covered a two part lease belonging to Fairstar Resources- a large area in the south and a small block in the north just above the old Kurnalpie townsite. It was obvious to us that being only an hour from Kalgoorlie, this famous area would have had an absolute caning over the last 20 years, but we still wanted to check it out.
On the first day, a guy drove into our camp on a quad and gave us a rundown on the place around where we were camped. He said “there is gold here, but you have to do a lot of walking to find it, there is no rhyme or reason to where you find it and there is seldom another nugget within cooee of the one you find”.
That all turned out to be pretty correct. We walked out from camp and found a couple of pieces around 1-2 gm. Next day I started walking and had a 2 and a 3gm piece by the end of the day.
Next day we explored the Northern lease, as I had seen pushings on it when studying Google Earth. I found four bits on the piles up to 0.5gm, but my mate Haggis hates doing the pushings, so we left. He calls me a seagull – always looking for peoples cast-offs !
We walked for hours that afternoon in the areas where we had found gold previously. We found nothing and decided to leave and get supplies in Kalgoorlie, have lunch and head off down to Mt Monger.


Mt Monger
This area used to be dominated by two Companies – Integra and Silver Lake Rersources. Last year Silver Lake successfully launched a takeover of Integra and now hold 90% of the land area around Mt Monger. There is a number of small active mining leases though and these should be avoided.
We spent a couple of fruitless days detecting south of the Wombola open pits. There were plenty of old mines, but bugger all detector holes. We found nothing there, either out wide, or on the heaps. We thought that maybe the lack of detector holes might mean that the gold mined was not of a nuggety type, but rather a more disseminated style spread through the host rock as fine grains.
We tried up around the Trans Line Rd at Majestic for no luck either.
Then we spent time on a number of pushings we had found on Google Earth north West of Fingal’s open cut and on an area south of Fingal’s. Both areas had had an absolute caning from detectorists, but there always seems to be a bit left in these places if you go low and slow.
These two areas produced a few nuggets out wide of the mined areas, but only in the 1-2gm range. Being a good seagull, I worked many piles and pushing and got over 40 pieces here in the 0.1 to 0.6 range with my trusty 12x7 Nugget finder.

Summary
We had a good time on the trip, but we had a discussion on the last night at the campfire and decided when we came back to the WA Goldfields in 2014, we would not revisit any of this years spots.
I had 28.8gm (65pc) for the trip and was happy enough I guess, as these had mostly come from only the last ten days of our trip.
I am already planning next year’s trip – you have to have something to look forward to.

Two Notes
JUNK PUT BACK IN HOLES
I used to think that people who left junk in their holes were creeps. I have changed my mind dramatically. Now I love people who leave their junk in the holes.
When exploring new areas, it is a great help to know if a detectorist actually found gold or just junk. Unless you are right on the side of a shaft etc, most junk in WA ends up back in the hole, so a quick swing gave us the valuable feedback we needed to build up a picture of the area.
In well detected areas in Victoria and WA, I will continue to remove my junk. In remote, less detected areas, I will return it to the hole.


“Lead shot has such a nice sweet sound – just like gold “ WRONG - it does not !
We detected a broad open pit about 100m in diameter. We nicknamed it the Pellet Pit and at one time I got 8 pellet targets in 2metres. Now people say they cannot tell the difference between the sound of a leadshot and the sound of a small gold nugget.
I think that is crap because I could tell 99% of the time when it was leadshot. I got so good at, it I did not even check the dirt when I had scraped it out. The only time the little blighters had me guessing, was when they had been knocked out of shape when they hit something. If they were nice and round it was not a problem.

Willie


I just copied this from the gold forum I am on. If you want to see the photos, go here :
http://golddetecting.4umer.net/t16015-four-weeks-in-june-on-the-goldfields-of-western-australia


AnswerID: 586040

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