how do they locate gold?

NewbieAgent

Good day sirs.
I was wondering, how is gold located?
I mean, do they use any machine to locate it
I am referring me to depths of over 10 meters up to 2 kilometers

Simon Bridge

You can use geology to provide clues ... eg.
http://earthobservatory.nasa.gov/Fea...ERProspecting/

There are several methods but for deep deposits you just guess and start digging.
If there were a machine for finding gold, dowsing wouldn't be so popular.

turbo

Placer-mining is popular. As the sizes of the nuggets increase, keep heading in that direction to find the lode. Panning is popular here in Maine, and I ran into a few guys from a fire department that take their vacation together yearly and hand-dredge a river in Byron. They have a mechanical separator that looks pretty cool. One of the guys told me that they could usually get enough gold out of the river to pay their vacation expenses. That's a good deal. They get to "get away", entertain themselves with the possibility of hitting a "honey hole". All good.

Simon Bridge

Pretty cool ... do any of these methods uncover gold deposits more than 10 meters deep as per OPs question?

I have a feeling that it is mostly guesswork relying on geological processes to bring some of the gold to the surface in a way that hints at a bigger load still down there.

NewbieAgent

That is very cool dude.
Ok, what if i build a metal detector, can i "manipulate" the metal detector so that i can get readings below 10 meters?

Simon Bridge

Then you'll get returns off any metal in some range below 10m.
Hmmm ... wonder how strong that would have to be to get a decent return through 10m.

You specified "gold", anyway. There are a lot of other metals in the ground.

You can also look for seams seismically or use ground penetrating radar, if all you care about is "is there something under there to dig up?"

turbo

@OP: I doubt that there there is any electro-mechanical equipment to give you an advantage at any depth. A metal detecter used in an alluvial flow can help you find dust and nuggets. Gold is very heavy, so the bigger the nuggets, the closer you are to the lode.

You would be best advised to learn the geology in your locale. Around here, gold is often found intermingled with quartz. YMMV.

Straw_Cat

To explore for deposits using placer mining techniques, you follow a watershed containing placer gold upstream. Pan the gravel beds in the river, and the deltas deposited by each stream entering the river. If you obtained traces of gold in one stream but none in the next streams upriver, you've passed the source. Go back and follow the gold bearing side stream(s).

At this point, you look for evidence of volcanic rocks, especially evidence of hydrothermally deposited minerals, since gold is usually deposited by hydrothermal vents: those are the 'black smokers' one seas on the ocean floor.

Japanese geologists, in fact, found one hot smoke that is depositing a rich seam of gold somewhere off their coast: I saw the colour video of this, but I don't know the scale of what I saw. This deposit will probably be left where it is since the Japanese won't say much except that it is more than 5,000 M below sea level. Therefore It would cost more to mine the deposit than it's worth. *

A rule of thumb is that one ~might find~ gold in a stream or deposit which has black sand (magnetite) but one will never find it if there is no magnetite (FeO3.)

Metal detectors can't differentiate very well between metals, as far as I know.

*Ordinary sea water has gold in it, and it can be recovered if you know how. But the latest figures indicate it would cost in excess of about $3500 an ounce to recover a mineral worth (now) under $1600/ ounce, and the price will probably drop in the future. Again, not cost effective.

Another way to find gold is by biopropspecting: some plants are known to accumulate metals in their leaves and stalks, and one tends to accumulate gold. However, I don't know which plant this is. A search for 'bioprospecting, gold' may provide an answer.
In this method, certain plants are havested, dried, and burned (probably in an oxygen-low chamber), and the ashes are analyzed for metal content. I'm pretty sure this is too expensive to do more than find indications of gold showings.

turbo

That's pretty much the procedure for placer-prospecting. If you can find a stream that yields nuggets (not just dust), follow that upstream and DIG in the gravel beds downstream of boulders. You might not find a lot of gold that way, but is surely more profitable than mining hard-rock and just hoping. Let mother nature do the hard work for you.

Straw_Cat

There was one guy who moved to Spences Bridge, B.C., in the 1930's or so, and found a cabin by a creek running out of the mountains. He set up a flume and divverted water from that creek into a barrel. The barrel was line with a wool blanket, and every few days he'd take the blanket out and put another one in. He'd wash the blanket in a big tub, and this released all the sand and such that was captured by the blanket. He'd then pan that and recover the fine gold dust in the sand, what we call 'flour gold' in this country. He managed to support himself by doing this for decades.
The down side of this, compared to finding nuggets, is that the old timers used mercury to amalgamate the gold. Nowadays one would use aqua regis or something of that sort. I watched a goldsmith use it (or nitric acid?) to recover gold, but I haven't bothered to research the chemistry behind it.
To purify the gold, melt it and alternately use baking soda and Borax powder as fluxes. After a few go-rounds, you'll have 24 carat gold.

NewbieAgent

Because gold is a very "money giving" substance.
And i have a taste for geology

NewbieAgent

Ok mate, i will do that ;)
I don't know much about finding resources "hidden".

NewbieAgent

Thanks a lot for your answers.
But that doesn't clarify the answer

SpaceDreamer

For mining applications, a small drilling rig is often used to drill small sample holes to test how much gold is likely in that specific area. Geologists will also attempt to locate veins of gold ore or rocks and minerals that are commonly found with gold. Magnetic sensors could also be used to detect large amount of minerals in the ground. For small scale prospecting, learning about local geology and how hold forms and what it is commonly near along with a sensitive metal detector could work. They can differentiate between different metals. Otherwise a small drill on a truck taking core samples or just digging a hole may be what you want.

Evo

Please post the link to the paper(s) on this. That would be helpful.

Evo

This is the USGS page on prospecting for gold in the US. OP, you should look for similar resources in your country.

http://pubs.usgs.gov/gip/prospect2/prospectgip.html

SpaceDreamer

The information comes from my own knowledge and interest in mining and prospecting, I have studied how mines work and how to mine, once had an idea to go mine gold in Alaska or elsewhere and am interested in resource excavations. There are no papers that I can link too and if it is in someway violating physic fourm rules please tell me.