# Mojave Ore Sample



## Chondrule (Mar 16, 2015)

Hi folks,
I've never before messed with ore or hard rock mining, so haven't a clue what I'm looking at.

This 91g sample is from out in the middle of the Mojave, from a hill where extensive tunneling and mining took place, so I know they were after something, just don't know what.









When at the mines, and again not knowing squat about ores, I tried using common sense to figure out what they were after. The tailings piles were chock full of big chunks of white quartz from the veins, so I figured they weren't after that material. Likewise, the piles also contained a lot of the other materials, such as the green stuff which looks like candy, so again I figured there was no interest in that. The only material absent from the tailings was the orange, yellow, or black ones, so this is what I spent my time trying to locate a sample of.

Does this look at all promising to you guys for containing gold? and if so, should I go the route of grinding it up, roasting, treating with nitric, treating with aqua regia, and dropping with SMB?
Keep in mind I have no furnace or means of smelting, thus why I've looked at trying to do this with acids.


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## FrugalRefiner (Mar 16, 2015)

I have no idea if there's any gold there, but they may have been mining copper or the copper based minerals. I can't tell from the pictures, but that may be chrysocolla which is quite saleable to rock hounds. It might be some other mineral. There are many that occur together, including malachite, azurite, etc. If you find a Gem and Mineral show, you could probably find a buyer for that specimen.

Dave


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## METLMASHER (Mar 16, 2015)

Nice!

#1 photo; bearing copper, quartz as micro-crystalline quartzite, also var. : agate, and appears to contain higher iron, although possibly desert varnish,if so, content unknown.

#2 photo; same with added chrysocolla ( the blue ), Chrysocolla is a hydrated copper cyclosilicate mineral with formula: Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (x<1) or (Cu,Al)2H2Si2O5(OH)4·nH2O.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0CC4QFjAF&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FChrysocolla&ei=yCgHVdX2OsvsoAS7s4CQDg&usg=AFQjCNGqLbrn-0FDqtfBUJr3Dt_K6D2yPw&sig2=KK2PPfqJ7XH_luCjwUKqlQ&bvm=bv.88198703,d.cGU

#3 photo; appears to contain higher iron, although possibly desert varnish, if so, content unknown.

#4 photo; lower right quarter of photo has visible gem silica. I'd like you to find me a chunk of said material, and post on the selling / trading forum. There is a definite market for that.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR3.TRC1.A0.H0.Xgem+silica+rough.TRS0&_nkw=gem+silica+rough&ghostText=&_sacat=0

Find the high content silica areas nearby, especially high concentration agate and crystal occurrences, and dig! There's money there, follow the links.

This may not have occurred to you, but there may even be gold and silver there. :mrgreen:


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## g_axelsson (Mar 16, 2015)

Looks like a piece of copper ore or copper mineralization. This type of mineral assemblage is usually created in the oxidation zone of the ore, creating secondary copper minerals from the mineralization when it weathers.

My guess on the minerals are
- Strong green : malachite (copper carbonate, quite soft compared to the other)
- Bluish green to pale green masses : chryssocolla (copper silicate, harder)
- Black patches : tenorite (copper oxide, thin crusts)

This is the type of rock you would see in the top zone of a copper mineralization. Here the primary copper mineral (probably a copper iron sulfide as chalcopyrite) has weathered and the mineral rich fluids would have deposited new minerals. When going a bit deeper into the mineralization the secondary minerals becomes less common, instead you find fresh sulfide minerals.

If there is any gold or not, only an assay can tell unless there is visual gold.
To extract gold chemically from ore on a small scale is a loosing proposition. The cost of chemicals will exceed any gold value extracted. This has already been written so many times here on the forum so I leave that as an exercise in searching the forum.

Normal gold content of ores is in grams per ton so your 91 gram rock would contain 91/1000000 = 0.000091 g gold per (gram Au per ton). Even if the rock would contain 10 g Au per ton the total gold would be less than a mg, virtually impossible to extract and melt into a visual grain since losses to filters and so on would add up too.

Keep it as a nice rock you found on a trip in the desert. By any chance, were you looking for meteorites? That style of scale cube is common among meteorite collectors and hunters, got one my self. 8) 



METLMASHER said:


> possibly desert varnish


Desert varnish is a smooth surface covering of mixed oxides and clay minerals. It is deposited on exposed surfaces over long time. These rocks are ragged and obviously not from an exposed surface polished by the wind so by definition not desert vanish.
http://en.wikipedia.org/wiki/Desert_varnish

Göran


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## Chondrule (Mar 16, 2015)

You nailed it Goran, meteorites are what I'm into, and thanks for putting things into perspective, using acids to get a trace of gold I wouldn't even be able to see doesn't make any sense.

As far as desert varnish is concerned, that's something I'm extremely familiar with, and these samples definitely have none.

METLMASHER, I'm not interested in selling any of this stuff, just wanted any gold out of it if possible, which looks to be a lost cause at this point, so what I'm getting at is, you can have the sample for all I care, I'll send it to you if you want.

The first images I posted are of a small chunk, a chunk I cleaved off the one and only sample I brought home from the field.
Here's the other portion of my original sample, it weighs 263g.









This blue and green copper mineralization stuff was abundant, but since I didn't think this material was the primary target for the mining, I didn't keep the better examples I ran across. The above example is nothing compared to what I left behind, there was way better.


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## FrugalRefiner (Mar 16, 2015)

Find a mineral dealer. It may not be the gold so many value, but if you have better specimens, you can make some money with that material. The rock hobby isn't what it was in the past, but there are still plenty of collecters who would like that stuff.

The biggest show just wrapped up in Tucson in February, but there are others. Denver has a show coming up in September. Those old miners might have overlooked some of the "gold". If you don't want to fiddle around with that stuff, let me know where that hole is.  I'd love to come digging!

Dave


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## METLMASHER (Mar 17, 2015)

Hey guys. A word in my defense. The amounts of varnish may be indeterminate in an unknown sample, and that not readily seen, even with decent photography.

Many times, though it looked like a pile of rocks, same as any nearby, I would turn them over and realize that the surface had developed a slightly darker coloring, from weathering in the Arizona sun and wind. These instances were surprising to me, having had so little experience with varnish, and expecting the stone to be _lighter_ on the exposed surfaces, not _darker_. ( Counter - intuitive. )

I must admit, full varnish _is_ a state that is *obviously* different, than the surface of the sample presented, but since I didn't know if it had weathered _at all_ in the sun and wind, I chose to mention the *possibility* of slight discoloration; due the processes of varnishing.

It begins with micrometer amounts and would, be virtually undetectable in the beginning, especially by photos.

Chondrule, I appreciate your offer, but would decline, with the caveat; if you go back, bring one of the larger agatized pieces. I'd be able to use 1/4 thick, by anywhere from 3/8" sq. and over.

As for gold, I made a joke earlier, and should first answer as best I can, or not post. The forum has changed *a lot*. 

There is most likely gold, in some amount, there in the tailings piles. The fact that they're tailing would be the first clue as to the value though. That said, if you crush, powder, roast, concentrate 50 pounds of the most mineralized on a shaker table, then smelt, and cupel. A good sample of values will be available for your estimation. The setup is expensive, but will pay for itself, if finding a good source, and fire assay is a goal.

The other members are right to a point. Small scale, it's a loser = usually. The fact is there may be 1/2 ounce per ton, and since we can't say one way or another, some amount of concentration, and a realistic estimation of both the amount of ore available, and the quality, will be fastest by fire assay.

Be well.


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## DarkspARCS (Mar 22, 2015)

with regards your samples Chondrule indeed they may possess values that may be extracted. in this case my recommendation is that you crush your ore if you choose to and concentrate it's values then go from there. You must understand that EVERY ore body is chemically different and thus needs to be scientifically examined so that the best course of action in economic profit can be discovered.

I would like to invite you to review my efforts located on within this thread: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=44&t=8709

Another Thread to review on this is: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=44&t=7842&start=20

You stated that you allocated your samples from the Mojave desert area. I'm located in Las Vegas, if you choose to PM me and we can discuss this further...


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## Richard36 (Apr 8, 2015)

What you have found is the mineral Smithsonite, which is a Zinc Carbonate.

Lead and Zinc deposits are often intimately associated with Gold and Silver, 
and form at the furthest zone of enrichment from a hydrothermal vent, and deposited by percolating hot water solutions..

I'd love to have a chicken egg size specimen for my mineral collection.


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## Ore/er/no? (Apr 11, 2015)

I dont know if this is where I should post this.I just want to know if I have something worth 
messing with or not the acid test stuff does not affect it.Or does anyone know somewhere in north phx I can have this checked out.


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## g_axelsson (Apr 11, 2015)

Ore/er/no? said:


> I dont know if this is where I should post this.I just want to know if I have something worth
> messing with or not the acid test stuff does not affect it.Or does anyone know somewhere in north phx I can have this checked out.


Looks like sulphide minerals to me. (It doesn't become ore until you have quantities and levels that can be mined economically.)

You should look into assaying, acid testing is for gold objects, not minerals.

Göran


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## butcher (Apr 11, 2015)

An assay needs to be done, an alternative to help identify what elements you may have in the ore can also be done with acids and reagents.


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## galenrog (Apr 12, 2015)

Testing is absolutely necessary. Many minerals and metals appear similar prior to recovery and refining. Learning, or at least being familiar with, proper testing procedures such as those suggested by Butcher are very important. Knowing what is in the ore can save a lot of trouble and unnecassary work.


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