Prospecting in a Portuguese Beach

[ShinyGoldPT]

Hi all,

I know a place on a beach that has a gold concentration of 9 grams per cubic metre, which is a lot , but i really new to prospecting so i have some questions. I know that the gold mesh is around 80 so would be pretty visible to the naked eye right?

I know that there is some small concentration of pyrite and i fear that i won't be able to distinguish the gold and the pyrite at 80 mesh size (even though i have 30 - 200x loupes), so i thought i could dissolve the iron in acid, but the only acid i can get is "muriatic acid" (hydrochloric acid) and i really can't find information about pyrite reaction in HCL, anyone knows if i can dissolve pyrite in HCL?

The last thing is: i can expect some flour gold for each scoop of sand right, because of the concentration / size?

I just want a gram or two for my collection

Thank you all

 

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[425jesse]

Hmmm, 9 grams....if there is 80 mesh there, then there is also 100-400 mesh there. Beaches are know for the superfine gold. Just my 2 cents, but I would check your resources. Get a pan, scoop some sand take great care in your panning. Pyrite will flow right out of your pan as it is way lighter than gold. Also gold is way prettier

 

[Capt Nemo]

You can pan that out easily, and seeing it won't be a problem. You'll have a bunch of flakes per pan.

Run away from any ideas using acid!!!

I'd love to hit that beach!

 

[KevinInColorado]

I agree with Nemo:
1. You'll be able to see it
2. The pyrite will move in the gold pan more easily than the real gold so you should be able to tell the difference.
3. The gold will most likely be concentrated in bands of heavier sand by wave action. Look for black/dark bands of sand on the beach.
4. Don't need acid, the loupe will show you that pyrite is cubic in shape and gold is soft, rounded shapes.

Finally: I will be in Lisbon and other parts of Portugal in April. I'd be happy to look at your material in person or maybe go panning with you if you like! (In which town are you living?)

 

[russau]

Kevin don't forget to bring us a vacation present!

 

[ShinyGoldPT]

first, Thank you all who answer my questions, i really appreciate it !

Well i knew i couldn't clean pyrite without some good nitric acid, which i don't or need to mess with, but i thought i would get problems with the separation at a so small mesh (80 - 400 like 425jesse said). I have two pan ( 8 inch i've bought on ebay), but what is really cool its the geology of the local and how the gold was deposited in that place and its full of fossils to !!! I can talk more about the place if you guys want.

About the shape, its alluval gold and they are toroid grains with elliptical shape, and you're right the shape of pyrite will help to eliminate her from my pan.

You plan to visit my small but big country? I live in Lisboa (Lisbon) and im more than happy to show you everything you want to know.

IM doing this with a friend who also wants a sample of gold, he lives like 1-2 km from the place so its really good to have 1 more brain and two more hands =D. The problem is that i live a bit far from the place and the bus and since i don't have a car i need to pick the bust which it's a bit expensive for my student pocket .

Will post some pictures as soon i get them!

Thank you all

 

[arizau]

Your toughest problem will be producing a reasonably workable amount of gold concentrates. Have you given any thought as to what you are going to use to do this? A gold pan for beach sand concentration is the most un-productive way to run volumes of beach sand* and if you have some type of sluice you will save yourself a lot of time and effort. After concentration a sieve/classifier set (30, 50 and 100 Mesh is my recommendation for beach sands) and a gold pan is probably your best solution to collect the gold contained. Classify your concentrates and pan each screen size separately. Gold is a little more than three times as heavy as pyrites or black sands of equal size and will separate pretty easily, with proper panning technique, when it is approximately the same size as everything else in the pan. It is best to pan the smaller mesh sized concentrates in small quantities even down to a tablespoonful at a time for the minus 100 mesh.

Good luck

*You can do it but it will take forever to run a cubic meter!

 

[mike(swWash)]

I'd love to see some pictures of the beach and close ups of the sand.
I do a bit of beach mining but with no where that much gold mixed in and might have some ideas that can help, as can many others here at Tnet for cheap faster production depending on the local rules.
[h=1][/h].

 

[Peyton Manning]

9 grams/ cubic meter?
is toad hoffman heading there?

 

[ShinyGoldPT]

HI all,

arizau, i just want a sample and i have no "black sand" just some ilmenite and some more heavy stuff like tourmalines, spinels, garnets and some more in really really low quantities, in Portugal i would get in trouble if i started to sluicing like a crazy ! Besides i don't have the material and i can only find in spain which costs a lot. I think im fine with my black pan, my shovel, my loupes and my good snacks ! I've watched a lot of information about panning gold and classification it's a good idea.

Mike, as soon i lay my hands on that heavy sand, i will take some good pictures. The problem is the portuguese rules, i can do some prospecting has long as i don't take huge quantities of the mineral.

Jeff, i don't know who is that Toad Hoffman, but iguess that there is better places than this one.

Fun fact : that place was a mine since the arabians invaded Portugal, another thing is that the king (D. Afonso Henriques) took 90 kgs of gold out of that mine, and i would be happy just with some grams...

Thank you all.

 

[Capt Nemo]

Your toughest problem will be producing a reasonably workable amount of gold concentrates. Have you given any thought as to what you are going to use to do this? A gold pan for beach sand concentration is the most un-productive way to run volumes of beach sand* and if you have some type of sluice you will save yourself a lot of time and effort. After concentration a sieve/classifier set (30, 50 and 100 Mesh is my recommendation for beach sands) and a gold pan is probably your best solution to collect the gold contained. Classify your concentrates and pan each screen size separately. Gold is a little more than three times as heavy as pyrites or black sands of equal size and will separate pretty easily, with proper panning technique, when it is approximately the same size as everything else in the pan. It is best to pan the smaller mesh sized concentrates in small quantities even down to a tablespoonful at a time for the minus 100 mesh.

Good luck

*You can do it but it will take forever to run a cubic meter!

All true there!

Constructing a small sluice or fluid bed, and a small miller table would be useful to speed things up.

I'm partial to fluid beds as they can be pretty compact even for a recirculator. With my model 4, I've run recirculating with the bed resting on a 2 gallon bucket pouring tailings into another bucket sitting in a 6 gallon mixing tray to hold the water. That's about the smallest footprint for recirculating. With a bed like this, you will have to classify the material to remove the pea gravel, usually to window screen. For every bucket of material run, you will need a bucket of water. The bed will give about a gallon of concentrates per cleanout. You can do about 24x 6 gallon buckets a day if you have to classify everything first. Power for the system is a marine/deep cycle 12V battery and a 800 gph bilge pump. There seems to be a specific size range that this system cannot catch very well. It appears that, that gold is too big to weasel it's way down between the black sand grains, and too light to brute force it's way down. Coarser light material (pea gravel) may also contribute to this loss. 80 mesh should catch with no problem. These beds are simpler to operate, as they're less sensitive to angle than a sluice. Roughly level to a slight down pitch on the tailings spout is good enough.

Model 4 (14"x6"x2.5" bed, 22" overall)


Mounted to 40 gal stock tank and solar panels.


A miller table will help you to get your gold clean and in the vial much faster than panning. The main table I have is a 14"x10" work surface. The green mat is the back side of a hobby cutting mat. I did scuff the mat with 400 grit sandpaper to give better holding ability. Other surfaces can also be used, like shelf liner, chalkboard paint, and slate. My table is also equipped with a hole to move the gold into a vial. At the head of the table is the spraybar followed by the dam. Behind the dam, I put in some Scotchbrite pad and humidifier belt to help smooth and prevent bubbles. The dam smoothes the water out, and also regulates depth. I made the dam adjustable for both height and angle. The recirculating tank is a Rubbermade bin, and I built the top of the table table to fit into the handle. The cross bar also ties into the bin with 2 long screws to adjust for side to side angle and table pitch. Water is supplied with a 120V 180 gph fountain pump. For brushes I use white nylon artists brushes. I also added some LED gooseneck lights. For applying cons to the table, I use a cone nose applicator bottle with the tip cut off. The losses on this table depend on the shape of your gold. Wire gold will just keep rolling, and foil can catch in the current and fly off. I like to run flat enough to have black sand catch at the bottom of the table. It keeps the gold pretty much where placed on the table.



I'm in the process of building a mini table that's 9"x6". It's running a blue/black gasket material, and I built a sluice mat (vinyl runner) for it as well. It's an experiment with the mats. Hopefully, I'll get her finished today. Just have to finish the dam, and hook up the water.

 

[mike(swWash)]

I'm thinking a home made 12"X36" sluice using vortex mat and an 1100gph bilge pump run off a small lawnmower sized battery would process a lot more than you can pan but still be a very small portable recirculating set up, and can be run almost any where. Small in size and cheap to put together.

 

[Capt Nemo]

In dealing with gold bearing sands and government, just keep to concentrate only. In Michigan, they have a 15.5 gram limit per year. I never pan out the gold, and take the concentrate home. No warden is going to spend the time to pan a 6 gal pail to figure out if you're legal or not. They want easy money, and they don't want to work for it!

I heard from a local up there that the wardens have to ask the locals where the fire roads are during forest fires. They must not get out much!

 

[ShinyGoldPT]

Hi all,

Building a sluice box just for a small small sample seems too overkill for me, plus i think that would get me in trouble. I just want to fill a small vial for my mineral / fossil collection.

Thank you.

 

[KevinInColorado]

Hi all,

Building a sluice box just for a small small sample seems too overkill for me, plus i think that would get me in trouble. I just want to fill a small vial for my mineral / fossil collection.

Thank you.

We are going to get you some gold for that vial! Looking forward to meeting up Easter weekend!!

 

[johnedoe]

I can only dream of a beach with 9 grams per cu.yd.

This is about -150 mesh and what I have to deal with on my beaches.

 

[mike(swWash)]

Same here on my beach.......and at that gold to sand ratio, I'd be looking into whatever it takes to start legally processing by the shovelful this picture is probably equal to 1/4 of a shovel load from your beach.

 

[cyberdan]

a very small portable recirculating set up, and can be run almost any where.

Even here in northern Commiefornia?

I would really like to see your setup after you are done. I am 20 miles south of the OR border. There is so much black sand on the beaches. I did one sample and got 40% black sand.

 

[johnedoe]

Even here in northern Commiefornia?

I would really like to see your setup after you are done. I am 20 miles south of the OR border. There is so much black sand on the beaches. I did one sample and got 40% black sand.

Hi Dan,
I think mike uses a goldcube ... He has a high banker that he was working with for a while too .... Not sure which one he stuck with.

 

[mike(swWash)]

Now days when I go to the beach I use my highbanker with a 3' extension with both lined with vortex mat. Motorized is legal on Washington beaches and where I gather sand there's a creek near by to run my bilge pump, no recirc set up needed for me. Oregon has a non motorized rule below the grass line, but if you can find a culvert that runs under the highway, then there's your non motorized water source. As for California beach rules I have no idea


The area I dig in runs probably 80% black sand with thin layers of blonde sand. If it isn't at least 3" thick, I move on. It usually takes 20 minutes to shovel about 1/4-1/3 of a yd of sand into my pickup and 4 hrs to empty