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          PROSPECTING TIPS

 

This page contains various tips, techniques and other information that relates to gold prospecting.

Over the years we have had many questions asked about gold prospecting. These include details on gold, testing gold, conversion tables, specific gravity tests, cleaning gold, gold prices, special metal detecting techniques, and many more.

This particular page is devoted to such questions.

Index:

So you want to go Gold Prospecting

So you want to go Gold Prospecting with a Metal Detector

Gold - A True Fact

Information on Gold

Testing for Gold

Gold / Silver Weight Conversion Table

Specific Gravity

Number of Karats = % Gold

Cleaning Gold

Price of Gold in Australian Dollars

 

 

SO YOU WANT TO GO GOLD PROSPECTING

By David Cooper © 2011

To understand a little about gold prospecting, it is a good idea to have a brief knowledge of how gold is formed. I feel it is necessary to know a little about rocks and minerals if one is to prospect intelligently, instead of blindly and ignorantly.

Geology:     THE ORIGIN OF GOLD

Igneous or intrusive rocks are the most favourable for promoting the formation of ores. Experience has proved that in Australia generally the biggest gold discoveries have invariably been closely associated with igneous intrusions. Country that has been much disturbed by intrusions of igneous rocks is always more favourable for deposits of gold for these reasons. Where the stratified rocks are much folded, tilted, faulted, or erupted, it is correct to assume that the earth’s crust at that point is weak, and has not been able to resist intrusions of rocks, mineral fluids and disturbances from below.

When the stratas on the earth’s surface give way, eruptions and intrusions occur. Fractures and fissures enable hot waters, heavily charged with minerals, to ascend and deposit a wide range of ores. These waters, carrying minerals in a dissolved form, circulate through every ‘nook and cranny’, and frequently one chemical acts upon another, causing gold and other minerals to precipitate – that is, to fall to the bottom of the water and becomes a sediment. Gold, and other precious metals, has been deposited in this way.

There is the very closest connection between igneous rocks and ore deposits. Nine times out of ten ore deposits have some visible relation to a body of igneous rocks. In general, that part of the country, which is free from igneous rocks, has few ore deposits, if any, and it is generally only a waste of time to prospect in such country.

The reason for this is that igneous rocks contain far more useful minerals than sedimentary rocks. Further, igneous rocks intrude into sedimentary rocks commonly leave a fissure where they meet. Thermal waters forced into this fissure commonly result in quartz reefs. An ore deposit formed at the junction of an igneous and sedimentary rock is shown by experience to be a likely place to find gold.

Many of these igneous intrusions are narrow, like quartz veins in shape, and are called dykes. These dykes have been forced up from the molten interior of the earth, propelled by the steam they contain, and so push their way into and through the hard rocks nearer the surface. They enter these rocks along the lines of least resistance – along fissures, joints and fault planes.

There are many other theories, one is that gold is formed in solution and ‘grows’ around the host rock. Coupled with this, a recent observation that has been published in recent times was an article published in the Australian Journal of Earth Sciences in 1984 (pp 303 – 316) by the late Professor Allan F. Wilson of the Department of Geology & Mineralogy, University of Queensland who quotes that: " the presence of a supergene process that can upgrade the fineness of gold shed from quartz veins. On the other hand quartz-free nuggets of superior fineness can enclose pisolitic laterite (iron mineral) concretions or other soil detritus. Supergene gold has been found in the following forms: (a) octahedra crystals of very pure gold (0.5mm diameter) set on felted surface of manganese oxide or in puggy clays; (b) filamentous (thread-like) and arborescent (growing like a tree) forms in several types of decomposed rock; (c) dendritic or paint gold on cracks in weathered rock, clay and laterite; (d) gold impregnations of fossil wood and coaly matter; (e) some gold nuggets of mamillary form. Variations in the non-gold components of solid gold are thought to reflect the chemical properties of gold-bearing non-hydrothermal solutions."

It is not my intention to provide a full explanation of the processes in this short article, but you will find as you go along, gold can be found in a variety of situations.

One of the common known deposits of gold is ‘alluvial gold’ or sometimes known as water worn gold. This can be found as small flakes or in some cases be large nuggets that can be found in past or present day river systems.

As previously mentioned, millions of years ago, tremendous faulting, twisting and volcanic action occurred. These upheavals elevate the old river systems to the tops of mountains and others were sunken far below the surface of the earth. This caused the rivers, in some cases to run in a complete different direction, as we know today. Some of the ancient rivers were heavily enriched with gold. Where the current rivers cross or cut through, often an abundance of gold has been found. These types of areas are not the only source of alluvial gold, but in most cases have been the most productive.

The other known deposit of gold is called ‘eluvial gold’ which, in general terms, is gold that has been shed from a reef. These are generally known as Secondary Gold Deposits. Eluvial gold is generally ragged in appearance, as it has not travelled very far from its source. There are some other types of deposits such as: Colluvial or Hill Wash deposits, Deep Leads etc., but these will not be dealt with here.

The sixteen (16) most common rock types that can be associated with or those that could contain gold are as follows:

Andesite, Basalt, Dacite (Quartz in), Diorite, Gneiss, Granite, Jasper, Limestone, Quartz, Quartzite, Rhyolite, Sandstone, Schist, Serpentinite, Slate (Quartz in), Trachyte.  

To familiarize yourself with rocks and what they look like is to purchase a good ‘Rocks and Minerals’ book. There are many available from our large range of books.

When gold prospecting, there is quite a range of equipment that can be used to recover gold from the basic gold pan to electronic equipment including the metal detector. Some of the most popular equipment is described hereunder together with a general operation procedure for your reference.

THE GOLD PAN

10 1/2 Inch High Impact Plastic Gold Pan

Regardless of whether you are a new prospector or an old hand, the gold pan is still the most indispensable piece of equipment you can have. It is one of the first tools used in locating gold and is possibly one of the last used. The old type steel gold pans are still available, but recent technology changed all that with the advent of the plastic gold pan. These are lightweight and do not rust. They can vary from a single riffle to several riffles. The best ones are those which have a 90° riffle and is near impossible to lose any gold! Another important piece of equipment is a ½" aluminium sieve. This is first placed over your gold pan and enables you to sieve the very large rocks from your wash.

Other tools that you may consider using for gold panning are the following: shovel, pick, pry bar, crevice tool, gold sniffer bottle, a magnet and of course some large (?) bottles to put your gold in.

If you haven’t been gold panning before, the following information and tips may be of help:

Alluvial gold is gold that has been washed down in the course of time from reefs and deposited in the sands and gravels of creeks and riverbeds. Having settled down, your first job will be to pan the sand and gravel in the creek or river to get a ‘colour’ - that is, to prove to your satisfaction that there is gold at the spot.

Remember that gold is a very heavy metal – twice as heavy as lead. Water washes it down the creeks and streams and it naturally lodges under large rocks, in front of rock bars across the river, and in rock crevices. Try and get down to ‘bedrock’ the bare floor of the creek as this is generally the place you will find gold. (You will soon come to learn to recognize when you come to it. It is usually soft and decomposed just where the alluvial deposit rests on it, and in that condition it is often known as ‘pipe-clay’ on account of its whiteness. A few feet further down, however, the slatey structure becomes visible, the rock gets harder, and the colour changes to yellow, grey and other darker tints). Clean out the dirt from these places and carefully scrape it into your gold pan. It is no point trying the top layers of gravel for gold, as you won’t find it there!

The basic procedure for gold panning is as follows: Fill your gold pan half full of gravel and sand. Cover the dirt with water. Swirl the pan round in a circular motion, tilting it slightly so the muddy water and lighter material run over the side. When you have done this thoroughly, scrape off with your hand about an inch of the gravel on top. Owing to its great weight, gold will have sunk to the bottom of the pan. You again cover the dirt with water, and again swirl it around with a circular motion, spilling the water and the lighter material as you do so. Again you ‘rest’ your gold pan, throw out the larger stones, and scrape off another inch of dirt from the top. Continue in this way until you have a large cupful of dirt left in your pan.

Now change the method by only putting a little water into the pan, tilt at an angle, and move the pan to and fro, each forward motion washing a little more of the sand out of the dish. Finally, you will merely have a little black sand left, and underneath that will be your gold percentage there may be two or three small flakes or a pellet or two, the size of a grain of wheat, or a small nugget, or there may be only a pinhead of gold – or even none at all. Don’t despair – dig a bit deeper and try again.

There are several books available from our shop in the art of gold panning, but if you want to know a little more, please contact me and I would be happy to give you an instruction sheet.

THE CRADLE or ROCKER BOX

These, to my knowledge, are no longer sold commercially, but plans on how they are made are illustrated in some gold prospecting books.

A cradle is a device with which the old prospectors are familiar and will enable you to put through twice as much wash dirt in an hour as a couple of people could pan in a day. A basic cradle can be built with a couple of strong wooden boxes in a few hours. A cradle is a box arrangement about 3 feet high, with a hopper at the top. Into the hopper one person shovels the ‘pay dirt’. The other person rocks the cradle and bails water into it and keeps throwing out the stones that are too large to go through the holes in the hopper.

The dirt is washed through these holes and falls on to a tray set an angle. You can have one, two, or three such trays. The dirt is washed over these trays, and any gold that it contains is caught in the riffle bars at the foot of each tray and in the bottom of the cradle. The trays are also lined with a coarse carpet in order to catch the fine gold.

Once or twice a day – more often if you wish – you will have the pleasure of ‘cleaning up’. To do this, you simply scrape all the dirt that has been caught in the riffle bars and carpet and put it in your gold pan and wash it in the methods as described earlier. Your gold will be gleaming in the bottom of your pan.

You will have no difficulty in identifying alluvial gold when you see it. There is nothing else like it. Sometimes the "new prospector" will see golden flakes floating on the top of his gold pan and thinks he’s ‘struck it rich’ but alas! for him, this is generally mica. Gold is bright yellow and will stay in the bottom of the gold pan. If you are in doubt – hit it with a hammer and the gold will flatten. If it is pyrite (‘fools gold’) it will shatter. If it’s mica, you will find it will disintegrate between your fingers.

THE HAND SLUICE

Super Mini Sluice Box

The next step up from the gold pan and cradle if you want to process larger amounts of material is the Hand Sluice. These can vary in length from 3’ to 4’6" generally around 10" wide having a series of riffles on top to a gridded diamond mesh and a special carpet underneath to catch the gold. The sluice box can be raised on an approximate angle of 30° by packing stones underneath. At the head of the sluice box, place a bank of stones leading up to it so the running water can be channeled through.

If you don’t have running water, you can place the sluice box on the bank at a slightly more increased angle and run water down the box by the means of a bucket. When you have completed sluicing, remove the riffle tray and mesh. Place the carpet in a drum of water and wash any excess gravel left in the sluice also into the drum. Swirl the carpet around so it washes clean. Put all the fine gravel, black sands and gold into a gold pan and recover your gold.

THE MINI GOLD CONCENTRATOR

These are very popular and extremely effective as it can process gravel 10 to 20 times faster than the gold pan and can recover gold to near 100%. It consists of a 5 gallon (20 litre) drum into which a Retention Bowl is set approximately halfway in the drum suspended by hanger brackets. There is a lowered part in the middle in which the gold is trapped. A spindle is fixed in the centre into which the removable dish/sieve is placed. This dish has a scraper blade and agitator bars welded underneath to agitate the water and gravel.

To operate the Mini-Gold Concentrator, first fill the bucket full of water and then shovel the gravel into the top removable dish to be oscillated by hand which grades the gravel through the built-in sieve. Oversize material is discarded by lifting the dish from the spindle and tipping out. (Check this later with a metal detector to locate any gold nuggets or gold in rock.) After grading, the gravel falls through the lower settling pan where it is agitated to allow the heavier particles to settle to the bottom of the retention bowl. Waste gravel is expelled over the outer lip of the lower pan by a helical scraper blade to accumulate in the bottom of the bucket, displacing the water which can be reclaimed if water is in short supply.

When the level of waste gravel builds up to the bottom of the lower pan, the bucket is emptied and refilled with water. Simply replace the lower pan and the top removable dish and you are ready to go again. A tip is to remove the concentrate and gravel before refilling and put this into another drum which can later be processed by the means of your gold pan in the same methods described earlier.

THE GOLD-WHEEL

Gold Screw Automatic Panner

A more sophisticated piece of equipment for gold recovery is the gold-wheel. This is a revolving bowl powered by 12 volt battery using a bilge pump to draw water from the creek which goes to the spray bar in the centre of the gold-wheel bowl. Material sieved to ½" size is fed into the bowl at a slow rate. The bowl has a spiral groove leading to a hole in the middle. Centrifugal force drives the gold through the hole into a container placed at the rear of the gold-wheel. These units can generally process up to 100 lb per hour. They can also be used for dry material (without water) with varying degrees of success.

THE DRY BLOWER

Vibrostatic Dry Washer            Hand Crank Mini Dry Washer

If you prefer to go gold prospecting the ‘desert areas’ of Australia, such as in the states of Western Australia, South Australia, Northern Territory and outback areas of New South Wales and Queensland where gold was once found and processed by ‘dry blowing’ these machines are quite successful. The original versions looked similar like a wheelbarrow with a bellows attachment underneath! However, technology has caught up with these too! Dry Blowers or sometimes referred to as Dry Washers, are ideal for these areas where there is no water available. They are now available as a hand-cranked unit and are operated by turning a handle. Previous models were had a draw pull rope that operated the bellows. Life is made much easier with the new models. Dry Blowers, which are powered by a 3.5 hp petrol engine, fitted with a hot air induction system dries the dampish material. However, it must be noted that the use of the petrol driven units could be illegal in some states – please check with your state Department of Mines for the current legislation.

The basic operation of these units is that dry material is shoveled on to the classifying tray on top, which screens the larger material from the small. The larger rocks slide down the tray onto the ground (this should be checked with a metal detector) whilst the smaller material falls through the screen and is channeled into the riffle box. The bellows underneath forces air through a fine cloth and blows the material across the riffles which are positioned across the riffle box. The material eventually finds its way down toward the bottom and ends up in a heap on the other side of the dry blower! The gold stays behind the riffles. You will also find that there will be some waste material banked up to the height of the riffles, which acts as a trap for the gold.

At the end of the day, simply remove the riffle box contents and empty them into a drum for processing later in the day with your gold pan.

THE GOLD DREDGE

2" Backpack Dredge with Suction Nozzle

For many years it was legal to dredge the gold-bearing rivers throughout Australia, mainly in Queensland, New South Wales and Victoria. However, due to the stupidity of some people, dredging is now illegal in most instances in these states. Depending on circumstances, dredging may still be allowed in some areas with permission. Check with your state Department of Mines.

A gold dredge is basically a floating vacuum cleaner! It is generally comprised of 2 floating pontoons, a motor and pump unit at the rear, a centre sluice box and various hoses. Basically what happens is that water is drawn through a foot valve and hose attachment to the pump. The water is then pushed through another hose to either a power jet or a suction nozzle, which is joined to the sluice box. The river gravel enters the suction tip or nozzle and travels along a suction hose that ends up into the hopper box of the dredge. The material then travels along a series of riffles (on top of a carpet) along the sluice box. The gold and black sands collect within and behind the first few riffles whilst all the non-values exit the front of the box back into the river.

At the end of the day, run some fresh water through the sluice box to remove as much gravel as possible. The gravel acts as a trap for the gold. The riffle tray is lifted to gain access to the carpet. This is carefully rolled up and placed into a drum. Use a bucket to wash any excess gravel left in the sluice box and put this into your bucket too. Fill the bucket to the height of the sluice box carpet and swirl the carpet around so it washes clean. All that will be left is a bucket of gravel and gold. Again, use either a gold pan or a gold-wheel to separate the gravel, concentrates and gold!

THE HYDRAULIC CONCENTRATOR

Backpack Dredge with Power Sluice Conversion and Suction Nozzle

This unit is generally known as a Bank Dredge. The principle is similar to a gold dredge but is worked on the river or creek bank. It is comprised of a motor and pump unit, combined classifier and sluice box, suction nozzle and various hoses. There are two models available. The first is a hand feed system, where you shovel the material into the sluice box hopper. This then travels along the classifying screen allowing the larger rocks to slide off while the screened material passes through to the sluice box underneath. The water entering through a foot valve in the creek is pumped through a hose to the pump and is then transferred through another hose to the sluice box hopper. Within the hopper box is a spray bar that allows the water to mix with the material being processed. This in turn travels along the lower sluice box that has a series of riffles that trap the gold like the sluice box on a gold dredge.

The other model is similar to the above except that the material is sucked up with a suction nozzle that is fitted to the end of the suction hose. The other end of the suction hose is fitted to an inlet of the hopper box. The water from the creek is also transferred through a hose via the pump and is coupled to the suction nozzle. Both the water and the material travel together into the hopper box where it is then classified in the same way as the hand feed model above.

At the end of the day, to recover your concentrates and gold, use the same procedure as you would with a gold dredge. Again, please check with your state Department of Mines regarding the use of these units.

ELECTRONIC PROSPECTING

Electronic prospecting (or much better known as metal detecting for gold) is an exciting new development over the past few years in gold hunting.

I refer you to the next article:

SO YOU WANT TO GO GOLD PROSPECTING WITH A METAL DETECTOR

Also on this web page ...  this subject is covered separately (below) in detail rather than duplicating it here.

CONCLUSION

I do hope that you liked reading this short article, I could have made it far longer, but it should give you some idea of what gold prospecting is all about. It is a most exciting hobby and gets you out into the great outdoors and that’s what it’s all about. You never know what you will find but it’s the fun in finding it! ............ Good prospecting!

 

.....................................................................................................................................................................................................................

 

SO YOU WANT TO GO GOLD PROSPECTING WITH A METAL DETECTOR

By: David Cooper © 2011

 

Welcome again to the most exciting hobby in the world – Gold prospecting ... this time with a metal detector !

This can be a most profitable hobby providing of course, that you follow a few guidelines and that is what this article is all about.

Geology    THE ORIGIN OF GOLD

(Refer to previous article)

BOOKS ON GOLD

One of the best Australian books that should be read is:

  "Gold Prospecting" by Douglas Stone 

Gold Prospecting

Doug gives this information in layman’s terms. Another way to familiarize yourself with rocks and what they look like is to purchase a good rocks and minerals book. There are many available from our large range of new and second-hand books. (These categories both new and second-hand can be viewed on our BOOKS & MAPS page).

The "Gold & Ghosts" range of books written by David W. de Havelland (now out of print) provide valuable information on the old gold areas and include maps. There are 2 books written on Western Australia and 2 books for Queensland (Southern & Central districts and North/North-western districts). These should not be missed as it will save you hundreds of hours of research, which brings me to the next point …..research.

RESEARCH

This is one of the most important points that’s forgotten. It is not much point buying a metal detector then wonder where you should go. It amazes me sometimes, that some people buy a metal detector and that’s all - no tools – no maps – no books and they expect to find gold!

As previously mentioned there are many good books available from our extensive range of books covering every aspect of geology, gold prospecting, metal detecting plus many geological and topographical maps as well as "out of print" geological reports. If you would like to do your own research, just visit your state Department of Mines library where you will find all the information available. Be prepared to spend a lot of time pouring over the old reports and maps. Most of these are now not available for sale as a lot of them are now out of print, so the information that you want will have to be photocopied at a charge.

For your information, I have provided the addresses of all state Mines Departments and Telephone numbers (correct at time of printing) to save you looking them up. (Don’t forget to ask for the latest information on fossicking regulations and miner’s right / fossicking licences.)

These can be found by clicking on to AUSTRALIAN MINES DEPARTMENT CONTACTS in the left-hand side column of this page.

Another place where you can find information is at your nearest university library in the Geology Department. The people here are most helpful. Most departments have a museum that you can inspect during business hours – there is always something you can learn here.

For up-to-date maps see your local Department of Lands office, they can provide the topographical maps for most states.

You can also glean information about some of the early gold mining areas in the local historical museum – the locals can provide information where all the activity took place in the early days. Sometimes they have publications available that they have printed, these can be most helpful too.

EQUIPMENT REQUIRED

When gold prospecting, there is quite a range of equipment that can be used from the gold pan to electronic equipment including the metal detector that we will go into detail shortly. There is no need to take an army of artillery of digging tools with you, as there will be enough to take without loading yourself up with any unnecessary "stuff".

The main tool that you will need is a type of hoe pick – a point on one end and a flat blade on the other, a shovel, a plastic gold pan which you can hang from your webbing belt and possibly a lightweight geological hammer. If gold panning, a ½" sieve is a necessity. Oh! I nearly forgot - a pouch or bottle to put your gold in. Another useful item is a magnet to find those annoying small iron magnetic pieces of junk. We have available a small cheap magnet that you can glue to the top of your pick handle – it comes in real handy!

If you intend prospecting with a metal detector, you will find that these today are compact and light enough to operate in the standard hand-held configuration. That is, with the control box mounted directly on the rod which is connected to the search coil. The entire unit is then in one piece. Battery packs on some detectors can be hip-mounted which make it lighter. We can advise you accordingly should weight be a problem.

Another important point is that if you intend to be out all day away from your vehicle, it is advisable that you carry a spare battery pack with you. Murphy’s law seems to bob up when you least expect it – just when you find a good gold patch – the batteries run out!

If you are going "bush" prospecting .... the following check-list are the main things that you need to take.

PROSPECTING EQUIPMENT

Miners Right / Fossickers Licence (depending on State or Territory), Metal detector/s, Headphones + a reserve pair, Spare batteries, Spare power lead, Magnet, Gold Pan, Sieve, Tweezers, Geologist's Rock pick, Heavy-duty pick, spade/shovel, crow bar (if detecting in hard ground), small clear bottle (for fine specs of gold) and a big sack (for the big pieces).

SURVIVAL ESSENTIALS

Maps (of the area you're working in plus up-to-date general road maps), Compass, allow 4 litres of water per person, per day, plenty of food (if you are going completely "bush"). Cooking equipment including a can opener, Tent and bedding, Winter and summer clothing (depending on temperatures), First Aid Kit, Insect repellant, "Mosquito" netting, Hat, Matches, Knife, Notepad and pens, Hand Axe, Bushman's Saw, Signalling mirror, Length of rubber or plastic tubing to use as a syphon, Nylon rope, Wire and Cord, Candle, Solid Fuel Capsules, Groundsheet, Space blanket/s (Aluminium foil), Torch, Mobile phone and Mains (if you have a generator) /Auto charger.

VEHICLE REQUISITES

Petrol / Diesel, Fan Belt/s, Hoses, Tools, Water, Shovel, Jack, 2 spare tyres, Puncture outfit and tyre levers, Fuses, Engine oil, strong Tow Rope.

There could be a lot of other items that could be added to the list ..... but it's a start!

 

ELECTRONIC PROSPECTING

Electronic prospecting (or much better known as metal detecting for gold) is an exciting new development over the past few years in gold hunting.

In order to answer the many questions that you may have, let me briefly list those that seem to be the more common ones.

Firstly, one must remember that you are using a metal detector. There is no such thing as a ‘gold detector’ some units are labelled as such, but a "gold detector" would just locate gold only and no other metal – I am still waiting for one to be invented – and I think that will be a long way up the track – if it ever happens!

As the name implies, a metal detector will locate all types of metal whether they are natural metals like: gold, silver, copper and platinum as well as man-made metals like: iron, aluminium, brass, alloyed precious and non-precious metals. A detector will give a better reading for gold if it contains a higher percentage of copper, than gold if associated with silver.

WHICH DETECTOR IS BEST FOR GOLD PROSPECTING?

There are many brands and models on the market today which tend to confuse those people who intend to buy a metal detector for the first time. One of things that you must consider is to how serious you want to be.

A good basic metal detector for basic gold prospecting and treasure hunting are the Bounty Hunter metal detectors - Tracker IV priced at $295 or the Quick Draw II priced at $425.    Users of both of these detectors and have reported good gold finds, particularly in very trashy areas. However, it must be noted that these units will only locate gold nuggets from approximately 1/2 gram to 1 gram in size upward.

Other detectors that are versatile for both applications is the popular Bounty Hunter series (a) the Sharp Shooter II (with automatic ground balance) ... or (b) the Land Star.

These models have an ‘All Metal’ mode with manual/automatic re-tune ground balance ('Land Star'), and automatic ground balance ('Sharp Shooter II') plus three (3) Discrimination modes. The discrimination modes on these models can be useful for coin and treasure hunting in determining either ferrous (iron metal) or non-ferrous (non-iron metal) targets. However, it must be pointed out that the minimum piece of gold that can be detected with the standard 8" waterproof search coil is about 1 gram and larger in size. If you are detecting alluvial deposits, it is advisable that the special 4" Nugget search coil be used, as it will detect slightly smaller pieces of gold from about ½ gram. This detector is a good economical unit that can be used for a wide variety of applications from gold prospecting to coin/treasure hunting and beachcombing.

The Bounty Hunter range come with a 5 year Limited Factory Warranty.

For those of you who would like a good sensitive detector for detecting small alluvial gold nuggets, the Fisher Gold Bug 2 metal detector operating at around 71.1 kHz  locates extremely tiny pieces of gold.   However, if you decide to use this type of detector, you will have to make sure that the manual ground balance control is adjusted constantly to eliminate false ground noise – apart from that, it is an excellent prospecting detector.

Possibly the most popular detector for all-round prospecting is the Minelab Eureka Gold which features automatic ground balancing, three (3) operating frequencies (6.4 kHz, 20 kHz and 60 kHz) and an iron reject switch which can be useful in some instances to identify rusted iron metal. This successful detector is used by professional and part-time prospectors alike.

The latest "top of the range" detectors which no doubt you have heard about, are the Minelab GPX Series  metal detectors.

Before you rush out and spend well over $6500 for a detector plus say another $1500 on extra coils, batteries and leads etc please consider a few main points.

It is very rare for someone these days to buy one of these detectors then rush out a find their fortune in a hurry. 

Don't forget that metal detectors have been used on the Australian goldfields for nearly 40 years. 

It takes a lot of time and practice to learn the detector properly. The detectors of today are far more complicated than what they were some years ago ... so ... don't be disillusioned ... just stick at it ... it could take weeks, months or years ... it all depends what time you have put into it.

Now ... once you have done that make sure that you something about geology as this helps you to locate possible gold-bearing areas. Go to some of the well-known goldfields for practice with a cheaper detector just to get the "hang of it" not forgetting that hundreds upon hundreds of people have possibly been there before you.

Once you have done that and you feel that you are ready to take on the "world" you can then go out on your own and "go gold prospecting".

To get this far you would have to had to put together a lot of other things such as a reliable vehicle, camping equipment etc., food, vehicle spares and not forgetting fuel costs.   

My advice to make a check list for yourself and see what it actually going to cost you first before committing yourself as a "full-time" gold prospector.

                                                                     The GPX's will go deeper than any previous GP or SD (Super Detector) range of detectors. These detectors excel in areas of high iron-mineralisation particularly in Victoria and Western Australia. 

In Queensland we have found they work extremely well in the following areas: Clermont, Charters Towers, Pentland, Cloncurry and some parts of the Georgetown / Forsayth areas.

All of these units are exceptionally good detectors and go extremely deep – so be prepared some very large holes as the large 18" coil has been reported to have located targets up to 5 to 6 feet deep!

However, in perspective, it would be no point buying an expensive metal detector if you only intend going gold prospecting a few days of the year, as it would be most unlikely that you would be able to recoup the initial cost of your detector in such a short space of time. Yet, on the other hand, for those of you who would like to go prospecting a little more seriously, please consider buying a detector a mid price range, like the Minelab Eureka Gold  or even the Bounty Hunter Sharp Shooter II as these units would be far more effective – the decision of course, remains with you.

 

My friend and fellow prospector, Tony Mills of Gold Search Australia in Dunolly, Victoria with some of those fantastic Victorian gold nuggets !

 

GROUND BALANCING

In order for a metal detector to operate correctly, it must have a ground balancing control that nulls the effect of iron mineralisation in the ground. This is one of the most important controls on the detector. If this is not set correctly, you will find that you will get erroneous noises which will make it difficult to tell the difference between iron mineral and any metal including gold. With some detectors this will have to be adjusted manually whilst later models have an automatic ground balance which adjusts itself as you search.

GROUND BALANCE OPERATIONAL TIPS

For those units that have a manual ground balance control, use the following explanation as a guide. Generally speaking, the threshold control must be set at a faint hum where it is just slightly audible and this hum must be kept stable in order for the detector to operate correctly. You will find that if you swing the coil from side to side or raise and lower the coil to the ground, the threshold hum will either increase or decrease in sound. The Ground Balance control must then be adjusted accordingly one way or the other until the threshold hum is constant. On most detectors (whether they be single turn or 10 turn) use the following method: If the threshold hum increases in sound when the search coil is lowered to the ground, turn the ground cancelling knob anti-clockwise. However, if the threshold hum decreases in sound, turn the ground cancelling knob clockwise. The object of the exercise is to adjust the control until the threshold hum remains constant when you either raise or lower the search coil to the ground.

As previously mentioned, some detectors on the market have an automatic ground balance and it is only a matter of swinging or pumping your coil to the ground a few times for the unit to set itself automatically. As you sweep slowly the detector adjusts itself automatically to compensate for any change in mineralisation in the ground. There are certain other adjustments that may have to be made, but these are explained to you as we go along when you purchase a detector.

Some detectors on the market, have what is termed, an All Metal Motion mode, this can also be referred to as automatic ground balance, generally pre-set by the factory. This can be used quite successfully in most situations, but if the detector should become a little erratic due to the ground conditions, the sensitivity control should be reduced slightly until it becomes stable again.

WHICH MODE IS BEST FOR GOLD PROSPECTING?

The best mode to use for prospecting is of course, the ‘All Metal’ mode, which as it says, will locate all kinds of metal whether it be: gold, iron junk or other non-ferrous metals.

One important factor must be raised at this point, is a control that bears the word "Discrimination". It is possibly the most misunderstood control by the new prospector. If you are prospecting seriously, my advice (like all professional prospectors) is to dig every signal. Remember, gold in its natural state is not highly electromagnetically conductive. Depending on the size of gold nugget and to what position you have set your discrimination level to, you can easily reject it.

Gold in small quantities can occur with other sulphides if in a reef situation, so it is not advisable to use any discrimination as you will reject the gold!

Some detectors specially designed for gold prospecting could have a discriminator or an iron reject switch fitted, so again, please be careful how you use these controls as they are only effective to certain depths and again, you could lose your gold. Again, I repeat, the best motto is to "dig everything" as you can never be sure.

HOW DEEP WILL THE DETECTOR GO?

This seems to be the most common question asked: "How deep will the detector go?" I am afraid you will never get an honest answer … Why? … you may ask … I can’t really say how deep it will go (and no one else who knows anything about detectors can’t answer the question honestly either) as it depends on many varying factors. Some of these are listed hereunder:

1.    It depends on the iron mineralisation of the ground. Is it low, medium or heavy mineralised?

2.    Moisture content of the soil. Is the ground dry, damp or wet?  If it is damp or wet ... the better response you will get on gold and metal targets.

3.    Salt content of the ground (if working in Salt pan areas)

4.    Condition of your battery pack.

5.    The operating frequency of your detector (If you use a high frequency detector you will easily locate small targets but with limited depth but if you use a lower frequency detector you will locate larger objects at a greater depth).

6.    Size, shape and density of the target or gold nugget.

7.    How long the target has been buried in the ground. This mainly relates to man-made metals. For instance: A ferrous (or non-ferrous depending on its associated alloys) object that has been buried for a period of time will give a better (and deeper) response than if it freshly buried. The salts and acids in the ground attack the metal and this corrosion is absorbed in the soil around the target (commonly known as a "halo effect") thus giving a better signal.

8.    Size of search coil being used.

9.    Detector operator’s skill.

and ..... As I said, there are many other factors as well.

Therefore to sum up, the "rule of thumb" in regard to depth is: The larger the coil, the greater the depth on larger nuggets, whereas, the smaller the coil, a lesser depth but greater sensitivity on smaller nuggets.

HOW SMALL CAN A DETECTOR FIND A GOLD NUGGET?

Good question!

How small is a gold nugget?

That is a variable question with no real answer. A gold nugget is normally a piece of solid gold from about the size of a pea up. I’ll leave that to you to decide.

Getting back to detectors, a metal detector can find a piece of gold from about the size of a large pinhead. However, for a detector to locate pieces of that size, you must generally use a detector that operates on a high frequency. Those metal detectors which have been found to be successful are the Minelab Eureka Gold (in the 60 kHz mode) or the Fisher Gold Bug 2 metal detector.

SOME DETECTOR OPERATIONAL TIPS

Whether you are working a reasonably flat area, undulating country, mullock dumps or dry gullies, it is best to grid an area section by section as you detect it. Obtain some plastic tent pegs and some nylon rope. Grid the ropes to approximately 2’ 6" apart. The length of course depends on the type of country being detected. Try 50 feet to start with. This can be increased if desired.

When using a detector, detect one way and then at right angles. Once completed, detect diagonally two ways in the shape of an "x" – by using this method, you will not miss a nugget. Remember gold comes in a variety of shapes and sizes. Some can be lying flat in the ground, others can be on end or at an angle, so by using the above method, if you miss a nugget in one direction, you will find it in any of the other three directions.

If you have a detector which has several frequencies (i.e. Minelab Eureka Gold) my advice is to use the higher frequencies (60 & 20 kHz) first which would detect the smaller nuggets and work down to the lower frequency (6.4 kHz) which would give a better response on those larger and deeper nuggets. When purchasing one of these units, we provide an additional step-by-step operational sheet with a special gridding pattern.

If you are working the eluvial gold deposits, it is best to work the dry gullies, checking each side of the bank and the main bed of the gully. You will find that smaller pieces of gold will be found first. Once you find a small piece, you will generally find they will get bigger as you reach the top of the gully. Professional prospectors also take the time to dig "test holes" as they go up the gully and if there is water nearby, use their gold pan to check the presence of gold. You can also use a "dry panning method" if water is not available.

HOT ROCKS or COLD ROCKS?

Whilst prospecting, you will come up with (at some time or another) a "Hot Rock" (these are not rocks which have been in the sun all day!). It is a technical term for a rock (or small or large concentrations) that is more iron-mineralised than what you have set your ground balance at.

You will generally get a positive signal on a rock that doesn’t, or even looks like that it could contain gold. The thing you have to overcome in learning to deal with hot rocks is to put aside any fear that you might have of them and to forget the idea that you must eliminate them. What you must do is learn to identify them! That is, you must be good at telling the difference between a hot rock and a real metal target such as gold.

By now, you are probably realizing that a hot rock is considered "hot" depending upon its relationship to the ground it is found in. The greater the degree of difference in mineralisation, the "hotter" the rock. Therefore, the fact that the rock makes a noise is due to the change in mineralisation and can sound like a real metal target.

Some of these hot rocks are on the surface of the ground and are much easier to identify. Some are deeper in the ground and some are extremely small in size. Since they exist partly due to their relationship with the surrounding ground, they present a somewhat different problem everywhere you encounter them. Some hot rocks are too deep and some are too small and some not mineralised enough in relationship to the ground, thus, you will hear some and not hear others. You can obviously ignore the ones you don’t hear. There is a bit more to this subject that what I have written, but at least it gives you an insight of what hot rocks are all about.

This reminds me of an incident a little while ago, when an experienced prospector came into the shop and showed me quite an array of gold nuggets that he had found in Central Queensland. Mixed up were some chocolate brown pieces that showed no gold, my first thought was that he must like collecting ironstone pebbles, as they seemed quite heavy. To my amazement and after some discussion, I realized that they were in fact, solid gold nuggets completely covered with iron oxide! At a glance, one would have thought it was rubbish! However, I put them over a detector and sure enough, it was gold all right. The only way that you could have tested them otherwise would be to file one of the edges. One could have quite easily mistaken them for hot rocks – so you can never be sure until you fully investigate them!

Another rock that could be mistaken for a "hot rock" is a meteorite – these give an excellent response on a metal detector. You really know in most cases when you have found one – it gives a good solid signal. These can be very rusty-looking. You can generally identify them by their appearance and are very heavy. Inside they look like solid steel – don’t bother to try and break them – you can’t! If you think you may have found one, have an expert look at it.

The opposite to "hot rocks" are "cold rocks" (not those that have been out on a frosty night!) in fact, not many people have heard of them but they do exist! These can be a problem sometimes as well. A cold rock contains a lesser concentration of iron oxide than the ground being balanced out. Igneous rocks such as: Granite and Rhyolite can cause this effect, hence it gives a negative sound and signal. If you ground balance over a "cold rock" the average ground will react positively. In essence, most gold prospecting is done in areas of high mineralisation in which case the ground balance control should be turned slightly higher than the detector’s null tuning point thus creating hot rocks.

PIN-POINTING YOUR TARGET

Once you have received a signal, the next step is to recover your target! Sweep the search coil in an "x" pattern so you can pin-point your target. When using round coils, the detector will emit the loudest signal when the target is directly under the centre of the search coil. If you are using an elliptical coil, use the above method or alternatively, you can tip the coil on its front edge and you will be able to locate tiny pieces of gold with ease.

Gently use your pick to scrape away the few inches of soil and check again. Repeat this procedure slowly – don’t get too enthusiastic as many a fine nugget has been damaged, losing its dollar value particularly if you want to use it as a jewellery item. If it is a very small target that is hard to find, just take a fistful of dirt and wave it in front of your search coil until you hear the sound of metal and hopefully your gold nugget.

Make sure that you fill in your hole and that will keep the landowner happy!

NOW THAT I HAVE FOUND SOME GOLD NUGGETS – WHAT CAN I DO WITH THEM?

My advice to you is this:

If you want to sell them, a collector prefers to buy them in the condition that they were found. Please don’t fiddle around with them by dropping them into various acids otherwise you could ruin them. However, there are some exceptions – these are as follows:

  1. Wash them in warm good soapy water (or a mild detergent mix) and brush them with a medium bristled nailbrush or with a toothbrush if there are some cavities. Stubborn deposits of soil can be loosened with a toothpick.
  2. For tiny nuggets: Mix some water, 2 drops of detergent and 1 drop of household ammonia into an old plastic film canister and shake them for about 15 minutes while you are watching television one night. When removing the cap, don’t have your nose above it otherwise you’ll knock yourself out. Empty the contents into a small glass jar and add some clean water, replace the lid and give it a slight shake to remove any dirt adhering to the nuggets. Empty the gold onto a plate and leave to dry. Your gold should then be bright and shiny. If it isn’t, just repeat the process again. You may find some extremely fine gold on the bottom so just put this into a separate bottle.
  3. To clean nuggets encrusted with iron oxide. Mix 1 part Hydrochloric Acid to 2 parts water.  

NOTEAlways add acid to the water……NEVER water to the acid.

As for a time frame for leaving the nugget in the solution, it is a matter of checking it every hour or so until the nugget becomes clean. Make sure that you wash the nugget in clean water afterwards. Don’t leave the nugget permanently in the solution or else it could discolour! NOTE: Make sure that you do this in an outdoor environment.

WEIGHT CONVERSIONS

24 Grains = 1 pennyweight

480 Grains = 1 Troy Ounce

20 Pennyweights = 1 Troy Ounce

31.1035 grams = 1 Troy Ounce

CONCLUSION

As I have been prospecting and treasure hunting for over 50 years in Australia and overseas there is always something you can learn about gold prospecting. I find that by reading, valuable tips and old techniques come to light and they still work today, even in this modern electronic age. The old timers had it tough, but they sure knew where to find gold, and all they had was an old cradle and gold pan.

If it weren’t for them opening up the goldfields, we would be floundering around in the dark – so it is up to us to follow in their footsteps and prospect from where they started. With all the different types of equipment that is available to us today, we haven’t got any excuse not to find more gold……………Good prospecting !

 

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GOLD - A TRUE FACT !

For those persons gold prospecting in Queensland there is over 28 ½ Million Acres of gold bearing country.

For one (1) person with a gold / metal detector covering 1 acre in an 8 hour day and 7 days a week it would take over 78,000 years to complete !

What about the rest of Australia ?

The Answer:   300,000 years +/-

So ................... start moving now !!     

When you've finished .. let me know and I will then give you some more areas to detect ... from afar !!

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INFORMATION ON GOLD

Scientific Symbol for gold: au

Crystal system: cubic

Hardness: 2.3 (on Mohs’ Scale of Hardness .. of 1 to 10)

Specific Gravity: 19.3

Melting Point: 1945° F  or 1063° C

Atomic Weight:  197.2

 

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TESTING FOR GOLD

There are numerous ways for testing gold. Perhaps the easiest way for testing in the field is to use a sharp knife and scratch the specimen on a part, which won’t detract its value. The knife will score a mark, as gold is soft. Another way is to hit the ‘gold’ with a hammer and it will flatten. If it is pyrite the specimen will shatter.

 

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GOLD / SILVER WEIGHT CONVERSION TABLE

1 Grain = 0.06479 of a Gram

1 Grain = 0.041667 of a Pennyweight (dwt)

1 Grain = 0.0020833 of a Troy Ounce

1 Grain = 0.3240 of a Carat

15.4324 Grains = 1 Gram

24 Grains = 1 Pennyweight (dwt)

480 Grains = 1 Troy Ounce

20 Pennyweights Troy (dwts) = 1 Troy Ounce

0.06479 of a Pennyweight (dwt) = 1 Gram

1 Pennyweight (dwt) = 1.5517 Grams

1 Gram = 0.03215 of a Troy Ounce

31.10346 Grams = 1 Troy Ounce

155.51 Carats = 1 Troy Ounce

 

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SPECIFIC GRAVITY

If you have a specimen that contains gold, you can work out the weight of the gold by using the following method.

The formula for calculating Specific Gravity of a substance is calculated as follows:

                        Weight in Air                             (Divided by)

Weight in Air      minus (-)       Weight in Water

 

= S G (Specific Gravity)

The scales being used must be able to accurately weigh the specimen in air and water in grams, troy ounces or avoirdupois ounces.

For example: Our specimen weighs 4½ ounces in air and 4 ounces in water.

To calculate to specific gravity we use the formula:

Weight of specimen in air 4.5 ounces. Minus (-) the Weight of specimen in water 4 ounces.

    4.5             =        4.5          = 9  (nine)

4.5 - 4.0                   .5

If the specific gravity is 9 (nine) using the table the percentage of gold would be 82.39% in the specimen so therefore our specimen contains 4.02 ounces of gold.

The following table is for QUARTZ only and is reasonably accurate as a guide

However, if the gold is in ironstone or other rock a new table would have to be calculated. 

Some specific gravities are as follows:

Granite: 2.56 – 2.74; Quartz Diorite: 2.62 – 2.90; Diorite: 2.72 – 2.99; Basalt: 2.74 – 3.21; Serpentine: 2.80 – 3.10; Ironstone/Magnetite: 5.18; Ironstone/Haematite: 4.9 – 5.3

The Percentage (%) by weight of Gold in a specimen, when the Specific Gravity (SG) is known:

S.G.

% Gold

S.G.

% Gold

S.G.

% Gold

2.60

Zero

4.10

42.39

7.00

72.82

2.65

2.19

4.20

44.13

7.20

74.02

2.70

4.29

4.30

45.80

7.40

75.15

2.75

6.32

4.40

47.39

7.60

76.22

2.80

8.28

4.50

48.92

7.80

77.24

2.85

10.16

4.60

50.37

8.00

78.20

2.90

11.98

4.70

51.76

8.50

80.42

2.95

13.75

4.80

53.10

9.00

82.39

3.00

15.45

4.90

54.38

9.50

84.15

3.10

18.69

5.00

55.61

10.00

85.73

3.20

21.72

5.20

57.93

11.00

88.47

3.30

24.58

5.40

60.07

12.00

90.75

3.40

27.26

5.60

62.06

13.00

92.68

3.50

29.79

5.80

63.92

14.00

94.34

3.60

32.18

6.00

65.65

15.00

95.77

3.70

34.44

6.20

67.27

16.00

97.03

3.80

36.59

6.40

68.79

17.00

98.13

3.90

38.62

6.60

70.21

18.00

99.12

4.00

40.55

6.80

71.56

19.00

100.00

 

Another formula is as follows:

A = Air

B = Water

 

   A    

A - B

= S G

Divide 310 by the S G and take it away (minus - ) from 116 = % Gold

116     -     310      (Do this calculation         = % Gold

                S G       first)

 

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NUMBER OF KARATS = % GOLD

Karat

% Gold

Karat

% Gold

Karat

% Gold

1

0.0417

9

0.3750

17

0.7083

2

0.0833

10

0.4167

18

0.7500

3

0.1250

11

0.4583

19

0.7917

4

0.1667

12

0.5000

20

0.8333

5

0.2083

13

0.5417

21

0.8750

6

0.2500

14

0.5833

22

0.9167

7

0.2917

15

0.6250

23

0.9583

8

0.3333

16

0.6667

24

1.0000

 

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CLEANING GOLD

Without using dangerous chemicals, there is a simple way of removing the iron oxide from small specimens.

Simply put your small specimens or even a small quantity of ‘tarnished’ alluvial gold into a film canister with a small quantity of water, a couple of small drops of dishwashing detergent and about 10 drops of liquid ammonia. If it’s really bad, you can add a little more liquid ammonia. Put the lid back on and make yourself comfortable in front of the television and just shake the canister up and down for about half an hour.

Pour the all contents into a small bowl and run some clean water in it until clean. (Note! Make sure you have the plug in the sink before you attempt this just in case you have an accident and loose all your gold down the plug-hole!)

Another way to clean gold is to put it in an old china bowl and add some white vinegar just covering the gold and a couple of teaspoons of sea salt and give it a good stir. Leave it for about half an hour and inspect it. If the solution hasn’t removed the iron oxide by that time, leave it in for another half-an-hour. After 1 hour replace the old solution with a new solution. Wash your gold in clean water, return it to the bowl with a new solution and repeat the same process.

You can also remove the iron oxide with either Hydrochloric acid or Nitric acid but please be careful!

 

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PRICE OF GOLD IN AUSTRALIAN DOLLARS

 

[Most Recent Quotes from www.kitco.com]   This is the current GOLD PRICE IN AUSTRALIAN DOLLARS

 

Another way is as follows:

 

To get an approximate idea of what gold is worth in Australian Dollars – use this quick calculation:

 

Take the gold price in US $ (Let's say: $725.00 / ounce .....divide this by the current exchange rate for Australian Dollars.  

(For example: 85 (.85) Australian cents = 1 US Dollar 

(Always take off a couple of cents from the advertised rate to be more realistic)

 

Example: US$ 1300.00  divided by  .98   =   AUD $ 1326.53 per Troy Ounce.

 

To convert this amount into Grams.      Divide the Australian Dollar Gold price by 31.1       (31.1 grams = 1 Troy Ounce)

Example: $1326.53 divided by 31.1 = approximately  AUD $ 42.65  per gram

I know that the the above calculation is rather outdated as it is currently around the US$1,400.00 mark per ounce or $45.00 per gram which is in parity with the Australia dollar.  

When the Aussie dollar is down again compared with the US dollar we get a better price for the gold !  ... that's when the above calculation will come in handy again.

5th January 2011

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end