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Couple ? Regarding Black Sand And Gold


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Hello, 

 

I was out this past weekend with my Gold Monster 1000. Here is a picture of a rock that I came across that had crystals and what I believe is black sand. I have come across black sand by it self and has done the same issue with my machine. Reading and sounding hot and then a blank sound as well. 

1) I assume that you can find black sand like this still in a rock with Quartz.

2) Is is not true that usally when you find black sand you may end off finding gold as well because black sand and gold go together. 

 

here are four pictures of the rock.

 

Allen

 

az1.jpg

AZ2.jpg

AZ3.jpg

AZ4.jpg

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So that is in a sense "black sand," but what you have there is a quartz rock containing a high concentration of iron minerals. Sounds like it's magnetite, a very "hot" iron mineral and a very common one in the goldfields. It is also true that gold may be found nearby as it is an indicator of mineralized rock bodies in the area that gold may have hitched a ride up with. There is a saying that goes, "gold rides an iron horse." Meaning essentially that gold occurs often in setting where iron occurs. They are both heavy minerals, and heavy minerals in general are an indicator of possible gold concentrations, but iron is much more common with the planet Earth than gold is. So there is going to be a lot more iron found than gold.

But it looks like you're on the right track in that area. It's specimens like that in your photos that sometimes are found to have gold in them. I'd say stick to it. You'll probably hit a heck of lot more iron nodules/hot rocks before/during/after finding some gold. But this is the labor of the detector prospector. Remaining diligent in detecting habit regardless of nuisance targets. Because you only find gold if you dig at targets, so take every non-gold find as a check-up that your detector is still working and that your attention span hasn't wanned and you will eventually swing that coil over something exciting 😉

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It is funny you should say that. I found this little speciman that actually showed gold on the metal detector. This one was found with in a 1/2 mile from the others. The rock shows black on the outside. I have checked it twice on my gold monster 1000 at two different days and they both showed gold. I assume inside there is probable going to be gold to it. It is nice because it weights 24 grams total. have a look at the picture.

 

gold1.jpg

gold2.jpg

gold3.jpg

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Sand is just that - sand. So a rock and the minerals in it are not part of a discussion regarding "black sands." Rather, you have a rock that appears to have some dark colored mineral, presumably an ore of iron.

Sand that is black is not always "black sand," and just because you have "black sands" does not mean you will find gold. Iron ores are common and just like quartz, can be found in far more locations that lack gold, than those that have it.

Anyway, here is something I wrote for another thread that explains what "black sands" are...

 

People sometimes misread the term “black sand”. Black sand is a mining term and actually has more to do with weight than color. Black sands are the heavy mineral concentrate recovered when running any form of placer mining concentration system. The most basic version is the heavy mineral concentrate left in the bottom of a gold pan.

From the Glossary of Placer Terms in Placer Examination Principles And Practice:

BLACK SAND Heavy grains of various minerals which have a dark color, and are usually found accompanying gold in alluvial deposits. (Fay) The heavy minerals may consist largely of magnetite, ilmenite and hematite associated with other minerals such as garnet, rutile, zircon, chromite, amphiboles, and pyroxenes. In Western gold placers, the black sand content is commonly between 5 and 20 pounds per cubic yard of bank-run gravel.

Black sands are also concentrated by winnowing action on beaches derived from terrestrial sources like volcanoes or granitic intrusives... any source that can supply the requisite heavy minerals.

In this context simply looking at a beach or in a stream and seeing dark or black colored material is not finding black sand. Amateur gold prospectors often do this, thinking that seeing black colored material in a stream is a positive sign for gold. All they are often seeing is just material like black slate or shale gravels and sands, not actual black sand. Unless it is heavy material concentrated by gravity action and typically with a high magnetic component, it’s not black sand in the context of the discussion.

True black sands are usually very fine though I have encountered coarse grain black sands. The fine grain variety often has a glittering appearance due to the presence of many sharp edged crystals of the constituent materials, chiefly magnetite.

Sands concentrated by gravity action and containing a high enough portion of heavy garnet material which confers a reddish color are referred to as “ruby sands.”

Again, the key thing is material derived by gravity concentration and therefore very heavy, not simply color.

Here is a picture of some gold I recovered in a Garrett 10" gold pan along with the resulting heavy magnetic black sand concentrates. Click picture for larger view.

magnetic-black-sand-gold-panning-concentrate.jpg
Placer gold and black sand concentrates

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Wow, so much more to learn, but a great place to learn the facts.

Every time I come here I learn things my grandfather never got to teach me.

Thank you

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Last season while detecting nuggets in an ancient river gravels area I grabbed a pan full of beautiful red dirt mixed with ancient cobble and sharp bedrock just for the hell of it to see if there was any black sand, colors, or fines????  I've picked many nuggies from surrounding area where this sample came from...MANY!  On the way home I stopped by the creek and panned the sample and not a spec of gold or black sand...nodda!!!!  I did that for my curiosity and also to  inform a geologist as she was curios also...   I was kinda shocked at the no black sand at all as down by the creek I get plenty of black sand when digging/panning there.

Bottom line.....black sand doesn't always show up where gold is found.........and vice-versa

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Iron is the 4th most common mineral in the earth's crust, with many rocks containing significant amounts of iron minerals. Both igneous ( includes both volcanic rocks and crystalline rocks like granite) as well as metamorphic rocks (rocks changed by heat and pressure) commonly have significant iron and it often crystalizes out into tiny dark colored specks that are heavier and more durable than other rock forming minerals like feldspar and mica. The iron rich mineral specs are what make up black sand. Rocks that dont have much iron - like limestone or dolomite - are only rarely hosts that give rise to placer gold.
So iron and iron rich minerals are super common, while gold is super rare (gold is one of the rarer elements in the earth's crust).
A lot of iron oxides in quartz veins are the remains of what was once iron pyrite, but the sulfur is gone and only iron oxides remain.
As far as rocks which show "gold" on the GM 1000, that merely means that there is something conductive there and it does not have the magnetic properties of iron minerals. It could be gold but it could be other things too. There are some conductive minerals - not many but a few.

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