'gossan' vs. 'gossan cap'

[Boarteats]

Quick question for the experienced prospectors in the forum. Is the word 'gossan' synonymous with the term 'gossan cap'? For example, if I find rocks in a stream bed that are iron/manganese oxide/hydroxide concretions, are those rocks gossan even if they are scattered about and do not constitute a 'cap'?

 

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[Goldwasher]

no it's not

 

[Bonaro]

There is a saying "gold wears an iron cap". Many times when there is a underground ore deposit, there will be a highly mineralized zone above it consisting highly of heavily oxidized manganese and iron. This is called an "Iron Cap" also called a Gossen Cap.
What you have found might have been part of a Gossen cap but since it broke up and washed away it no longer is.

 

[Boarteats]

There is a saying "gold wears an iron cap". Many times when there is a underground ore deposit, there will be a highly mineralized zone above it consisting highly of heavily oxidized manganese and iron. This is called an "Iron Cap" also called a Gossen Cap.
What you have found might have been part of a Gossen cap but since it broke up and washed away it no longer is.

Thanks for the clarification!

 

[arizau]

Those pieces may explain why some of the gold you are finding have gone Johnny Cash.....wear a black coat.

 

[Boarteats]

Those pieces may explain why some of the gold you are finding have gone Johnny Cash.....wear a black coat.

Lol. I wasn't aware that there could be a correlation between these rocks and having gold covered in iron oxides. Guess it makes sense now that you mention it. I've been collecting/polishing chunks of these concretions for years. Have to break them up with a sledge hammer, because they're so damn heavy! Should I be crushing them up instead, looking for gold?

 

[Goldwasher]

Most of the gold with black on it I get is manganese oxide. The quartz does have a lot of Iron oxide in it.

it takes several baths in muriatic acid to pull it all out.

 

[Boarteats]

Most of the gold with black on it I get is manganese oxide. The quartz does have a lot of Iron oxide in it.

it takes several baths in muriatic acid to pull it all out.

I've got chunky manganese oxide as well. How long do you let the material sit in acid? Heated/cold?

 

[arizau]

Lol. I wasn't aware that there could be a correlation between these rocks and having gold covered in iron oxides. Guess it makes sense now that you mention it. I've been collecting/polishing chunks of these concretions for years. Have to break them up with a sledge hammer, because they're so damn heavy! Should I be crushing them up instead, looking for gold?

Tongue in cheek or not, I don't know that I would start with breaking up large pieces unless there is visible gold showing. Some of the concentrates (I assume you did some concentration?) that you have been, for another purpose, reducing in a mortar/pestle setup can be done in larger volume in an inexpensive home made pipe crusher similar to the one shown at the bottom of this page. Plan, Design and Build a Dolly pot; hand powered rock crusher. A capped piece of pipe, or whatever, that fits into the larger pipe does the job for many. Screen, pan, carefully examine and make the decision if what you are doing is worthwhile then maybe, for test purposes, break up larger chunks for feed and test them....overall, nothing ventured, nothing gained. If you decide to further pursue then your best bet is probably to work mainly with coarse sluice or panned concentrate rejects, eg. screen and pan it first for obvious gold.

 

[Boarteats]

Some of the concentrates (I assume you did some concentration?) that you have been, for another purpose, reducing in a mortar/pestle setup can be done in larger volume in an inexpensive home made pipe crusher similar to the one shown at the bottom of this page. Plan, Design and Build a Dolly pot; hand powered rock crusher. A capped piece of pipe, or whatever, that fits into the larger pipe does the job for many. Screen, pan, carefully examine and make the decision if what you are doing is worthwhile then maybe, for test purposes, break up larger chunks for feed and test them....overall, nothing ventured, nothing gained. If you decide to further pursue then your best bet is probably to work mainly with coarse sluice or panned concentrate rejects, eg. screen and pan it first for obvious gold.

@arizau, appreciate the follow-up! I'm sure that I'll get around to breaking up, screening, panning these rocks at some point.

 

[Goldwasher]

I've got chunky manganese oxide as well. How long do you let the material sit in acid? Heated/cold?

I should phrase that better.

For Gold and quartz with heavy Iron stain I do several acid- neutralize - flush cycles until the gold shows really well and the iron staining goes away.

For placer with an oxide coating heat and water takes care of it. The Muriatic should act on staining on gold also.

I haven't done any warm acid etching mainly because I haven't needed to etch off all the gangue material. I don't have a spot safe enough to set up and deal with stronger acids. Its also something I want to learn from someone else not the intraweb. As "simple " as it sounds.

With the specimens I get. They tend to be porous quartz so it sucks up the muriatic acid after eight hours I neutralize with baking soda and water. The pieces will bubble for several hours while the acid inside is still present. The quarts gets weakened enough on the little fractures that I can pick at it with a toothpick or a screw tip to groom off little chips and crumbs around the gold.

That's quartz. Calcite is harder. Would require stronger acid.

I also had a small bit of a product someone gave me a sample of its a paste or liquid stronger acid. Get the liquid not the cream. https://www.createforless.com/Armou...6854&catargetid=530001980000165791&cadevice=c

It acts on the quartz faster than the muriatic.

You may want to try heat and then water shock on some of your concretions see how that will break them up.

 

[Clay Diggins]

I haven't tried the glass etch you are using Goldwasher. I imagine it's slow but if it's effective that's what matters.

The big boy of cleaning gold specimens is Hydroflouric Acid. This stuff is nasty - as in you die a horrible painful death when you use it incorrectly. If you don't know what you are doing with this stuff and you survive your dangerous acid experiment you will more than likely ruin your first specimen by overdoing the etch. When you over etch you get a lump of melted quartz with a bit of native gold sticking out. That's interesting but not very marketable. This particular acid dissolves quartz and just about everything else, including humans, but it doesn't affect the gold. Finding containers and tools to work with can be challenging since both glass and metal containers dissolve in this acid.

Basically between the environmental dangers of storage and use just having the hydroflouric acid concentrate around constitutes a real hazard. Luckily there is a way to buy and use a very mild hydroflouric acid solution that can get iron stains out in a jiffy and can even do a genuine etch on the rock material given enough time. You are still going to have to wear gloves, have a fresh air supply and be careful when handling the solution but this stuff isn't really any more dangerous than pool acid. No kids, no pets, wear protective gear etc. and you will be fine.

The product is Whink rust stain remover. Whink makes a bunch of different products that might be good for other things but this particular version of Rust Stain Remover is the only one they make that has hydroflouric acid as an ingredient. It's always in a brown bottle but I seem to have a few different sizes.

Whink is not particularly expensive and with reasonable precautions you should be able to use this on your specimens at home. This will dissolve most minerals and metals so other types of specimen might react well too. Rust stains on quartz crystals clean up well and often a dull druzy can be brought to sparkling glory with just a short soak.

Keep in mind that the hydroflouric acid is not your only danger point. The chemical reactions between the minerals present and the acid produce fumes too. Many, if not most, of those fumes are very detrimental to human health and lifespans. You really need to assume whatever mineral you are etching produces poisonous fumes.

Heavy Pans

 

[Capt Nemo]

Beware of HF and sulfur. SF6 will insulate transformers, and is safe. SF2 will fumigate your house for bedbugs and maybe you too. SF4....You're dead before you even know you breathed it!

 

[Goldwasher]

I haven't tried the glass etch you are using Goldwasher. I imagine it's slow but if it's effective that's what matters.

The big boy of cleaning gold specimens is Hydroflouric Acid. This stuff is nasty - as in you die a horrible painful death when you use it incorrectly. If you don't know what you are doing with this stuff and you survive your dangerous acid experiment you will more than likely ruin your first specimen by overdoing the etch. When you over etch you get a lump of melted quartz with a bit of native gold sticking out. That's interesting but not very marketable. This particular acid dissolves quartz and just about everything else, including humans, but it doesn't affect the gold. Finding containers and tools to work with can be challenging since both glass and metal containers dissolve in this acid.

Basically between the environmental dangers of storage and use just having the hydroflouric acid concentrate around constitutes a real hazard. Luckily there is a way to buy and use a very mild hydroflouric acid solution that can get iron stains out in a jiffy and can even do a genuine etch on the rock material given enough time. You are still going to have to wear gloves, have a fresh air supply and be careful when handling the solution but this stuff isn't really any more dangerous than pool acid. No kids, no pets, wear protective gear etc. and you will be fine.

The product is Whink rust stain remover. Whink makes a bunch of different products that might be good for other things but this particular version of Rust Stain Remover is the only one they make that has hydroflouric acid as an ingredient. It's always in a brown bottle but I seem to have a few different sizes.

Whink is not particularly expensive and with reasonable precautions you should be able to use this on your specimens at home. This will dissolve most minerals and metals so other types of specimen might react well too. Rust stains on quartz crystals clean up well and often a dull druzy can be brought to sparkling glory with just a short soak.

Keep in mind that the hydroflouric acid is not your only danger point. The chemical reactions between the minerals present and the acid produce fumes too. Many, if not most, of those fumes are very detrimental to human health and lifespans. You really need to assume whatever mineral you are etching produces poisonous fumes.

Heavy Pans

And that is why I haven't messed with HF. My work area is outside and multi purpose. Dog kids around. No desire to melt down my lumps or my kids.

I have read about wink and should get some.

I used the glass etch on recommendation from someone else who was etching local specimens .

It is slow acting but, faster than the Muriatic.

I get stuff that isn't typically a solid mass , so something slow is nice I can clean them up step by step and stop when I like how the gold is showing.

I should get some wink though.