Acid to dissolve quartz ?

[BigWave]

Agree Atom. Good to keep up the warnings on this stuff! I've only used it on nuggets where I knew there was significant gold inside ironstone, and wanted to show it. I stop before significantly attacking any quartz though (per the pictures above), and leave just a little ironstone in deeper recesses to show some more character and origin. I have some pieces where I can see gold in quartz. They have a very high SG so I know there's much in there, but I leave them as they are for show and tell. Who knows, one day my kids may think differently and crush/melt them down. I hope not, but each to their own.

 

[Heatho]

I'm pretty sure HCL is a better acid for disolving ironstone from gold. The percentage of HF in Alibrite is very low but precautions still need to be taken.

 

[mbasko]

The percentage of HF in Alibrite is <1%. Follow the safety instructions & you'll be fine. If you can't follow instructions or don't feel safe using it then don't.
The MSDS for Alibrite states it contains no carcinogenic substances but just to be safe don't drink it, bathe in it, sniff it or use it as eyewash.

 

[bazxa]

Hydrolforic, not worth using for a bit of gold, you are of more value than that.

Barry

 

[The Green Wanderer]

Hi Peko,
I do know that Phosphoric acid eats concrete floors but not sure of how it would react to quartz.
Same rules as HCL apply, well ventilated and chem gloves etc. Just make sure it doesn't mix with a strong base ie sodium hydroxide or similar.
Personally id rather use thermal shock to split the natural fissures in quartz if I wanted to get the gold out whole.
On the other hand slices of a specimen with a good marbling of gold would make great jewelery.

Goodluck,
TGW.

 

[markgoldhunter]

g,day all, I have this specimen showing gold in 3 spots, they are all connected but , going by weight, not by very much, this may end up to be a nice very fine spidery piece of gold so I decided to drop it in allybrite. after about a month I took it out and there was no difference, so I have had it in hydrochloric acid for 2 weeks now and still no change in both cases there has been no sediment in the jar.

can anyone suggest the next step.

 

[Jaros]

If you have a heavy duty vice - giving it a slow crush might produce some worthy results!

 

[DrDuck]

Just out of interest, did you test for electrical continuity to determine whether the gold is connected?

I don't think Alibright is strong enough to cope with that much quartz, it is a very weak solution of HF acid. HCL is not up the job of dissolving quartz, either. The strong stuff is very dangerous and needs to be treated with abundant caution and very stringent handling protocols.

There are a few threads on the forum about using HF to clean specimens.

There could be a very nice piece of gold in there. Did you do a specific gravity test?

 

[mbasko]

Some previous discussion here:
https://www.prospectingaustralia.com/forum/viewtopic.php?id=1692
From anything I have seen hydrofluoric acid is the only acid that will dissolve quartz.
I've had some speccis where the quartz will become chalky & start breaking down quickly in Alibrite - even after a few days or so. Others seem to remain intact even after weeks in the Alibrite? Alibrite being a very low percentage of HF seems to only be effective mostly for cleaning or starting to break it down. It would take months to dissolve even the "chalky" bits I've had.
If you want to break it down or dissolve it entirely you'd need a stronger HF concentrate acid solution but IMO it's too dangerous for home use. If your sure the gold is joined maybe contact a lab? I've crushed etc. a fair few speccis & found that very few had the gold joined internally even though a lot show gold on various or all sides.
I've never tried the thermal shock method mentioned in the thread above but it might be worth a try.

 

[kawman]

The doc knows how to tell..

 

[AtomRat]

Make sure the allbrite you use contains hydrofluoric acid and not the phosphoric acid
Great thinking if you did use continuity to test the link between visible gold

 

[Guest]

I have used thermal shock method and it works...........

Heat it up till it glows red. The gold wont melt using a general purpose blow torch.

Drop it in water. It will become super brittle. Then slowly chip away at the quartz. Think small hammer gently tapping.

Repeat process till most of its gone, then back in Alibrite to remove trace amounts.

Let us know how you get on.

Cheers

RS

 

[BigWave]

Brilliant idea RS. A well known old-timers method I'm sure, but almost lost to our generation.

 

[mbasko]

I have used thermal shock method and it works...........

Heat it up till it glows red. The gold wont melt using a general purpose blow torch.

Drop it in water. It will become super brittle. Then slowly chip away at the quartz. Think small hammer gently tapping.

Repeat process till most of its gone, then back in Alibrite to remove trace amounts.

Let us know how you get on.

Cheers

RS

That's how I do my speccis except without the thermal shock, small hammer & gentle tapping. :lol:
Seriously though it's surprising how a gentle tap in the right spot can easily get the gold out intact anyway. I've broken a few up & left little bits of quartz attached as a base or because I liked the look of it.

The above (sorry for poor pic - cropped from a larger photo) were all broken out of speccis using a hammer, some rag (to wrap up the specci), multigrips & patiently/gently breaking the quartz away. In some cases when close to the gold you can break it away with your fingers. None of these were internally joined speccis though.
Brightened up in short Alibrite bath.

 

[BigWave]

Loving the look f your species mbasko

 

[mbasko]

Thanks BW - not mine anymore though. Those all went to new homes
Here's an example of one of the bits where the quartz went "chalky" after only 3 to 5 days in Alibrite. Don't remember exact time but it wouldn't have been more than 5 days in.

Only had 2 x seperate speccis go like this from the same general area though so maybe to do with the make up of the quartz? I still reckon it would take months for the Alibrite to fully dissolve even these chalky ones?

 

[Bjay]

Pickling paste has a much higher concentration of hf and works quite well but if unfamiliar with and you don't have the right gear and calcium creams and tablets just in case I would not recommend it. I have used before but now use the thermal shock method as its much safer and quite effective.

 

[markgoldhunter]

thanks for all the tips, I used a multimeter to test conductivity between the 3 spots on the face you can see and 1 speck on the back so I know they are all connected and though I haven't done a s.g. test the piece is very light so i'd be surprised if there is more than a gram of gold in it. I have heard of the thermal shock method before but never tried it so I think I will give that a go as stronger acids seem a bit too risky for me. nice gold mbasko that is the type of nuggets I am hoping to end up with. so I will post some more pics as we go. cheers.

 

[Phoenix76]

Mark, the thermal shock method is certainly an old timers method. Well demonstrated by a little story.

Mate and I have an old mining field here in Qld and one of the mines is still open although in disrepair and dangerous. However, history tells us that one miner on his own dug the shaft and hauled his ore to the top. He then burnt all of his quartz before crushing by hand. He is reported as having pulled 2 toz per ton. That is a bloody good return, and even better when conditions are taken into account.

And just to support what others have said, the effective chemicals are very dangerous and best left to people who know how to safely use them. I use them in electronic precious metals recovery and the attached photos will give you and idea of the gases that are given off during the process. All that brown smoke/gas you see is deadly and one breath can kill you.
Cheers mate

 

[Tathradj]

I think they called it " Roasting "
Made quartz fracture easily in a hammer mill. Instead of exploding like shards of glass
the ore would reduce to a fine powder.

Commonly used as in recovering molybdenum.