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New "acid" to remove calcite from specimens

Posted by Rory Howell  
avatar Re: New "acid" to remove calcite from specimens
June 30, 2011 10:07PM
    
I'm not inferring that the product doen't exist - it only has not much to do with what the name implies. In particular, it is not a hydrochloride - much in the same way as "thiurea dioxide" (another entirely misleading trivial name) has not much to do with waht the name implies but is a sulfenic acid derivative instead. Trade names, however, are often just conceived for obscurification.
Re: New "acid" to remove calcite from specimens
June 30, 2011 11:30PM
    
The label "synthetic acid" is a pretty silly term. In general, good old hydrochloric (muriatic) acid is a synthetic acid.
The only "natural" way to get hydrochloric acid that I can think of would be to pump somebody's stomach.
The usual marketing hype I suppose, insofar as calling something a synthetic acid would add to the products
appeal. I would still be careful with it, as has been said. For that matter I would be careful with acetic acid,
which is quite "natural"
Re: New "acid" to remove calcite from specimens
July 01, 2011 02:10AM
Hello,

Interesting this thread is running. I am about to post a new thread regarding acid etching.

Many in the Copper Country of Michigan use sulfamic acid, sold in hardware and home improvement stores as a solid that can be dissolved in water. It is faster than vinegar. That said I like vinegar. It is gentle and slow and if followed by generous and repeated soakings in water crystals of many minerals come out clean and not frosted. Sulfamic seems to clean copper and silver well but accessory minerals may not survive as well.

George
Re: New "acid" to remove calcite from specimens
July 25, 2011 01:05AM
    
Georg Graf Wrote:
-------------------------------------------------------

>
> little bit more precise: Essigessenz is pur, 25%,
> acetig acid.
>
I too used to use Essigessenz for calcite removal. But I found a much cheaper 25% acetic acid source at the local Korean market. It's in a liter size bottle and called simply 'concentrated vinegar' in English. It's less than $4.00 and and will dissolve a lot of calcite.

I first came across it searching for a safe weed killer, which it is when diluted 2:1. Blackberries are a noxious weed here and I use it so I don't incur the wrath of the park district which has the adjoining property.

Easy Goin'
USA
Re: New "acid" to remove calcite from specimens
July 31, 2011 02:37PM
Don't all strong acids get their mineral dissolution job done the same way regardless of dilution of the acid component ?

My haphazard experiments with acids and minerals over the years have produced many curious results which lead me to believe that a crucial factor is the composition of the solution as the reaction occurs.

For example, when dissolving calcite away from pyrrhotite, things work well for a while, and then suddenly, the acid bath starts generating hydrogen sulfide and the the pyrrhotite starts dissolving. I think that this is because the HCl solution has become a CaCl2 solution which must be corrosive toward pyrrhotite.

Here in King County, Washington we have wonderful locality for shiny dodecahedral magnetite enclosed in calcite. The darned things are always etched when I use HCl to remove the calcite. Maybe magnetite is soluble in a CaCl2 solution resulting from the interaction of calcite with HCl.

I'm going to try some other acids, including this now infamous "synthetic" acid.

Since we have all these chemists on this thread, I will impose upon them to explain why ammonium bifluoride is a more pleasant, yet effective substance to use for opaline crust removal on other silicates than even dilute HF. Doesn't it dissociate into the same thing?

I've heard some talk that I don't understand about ammonium bifluoride being "self buffering". Maybe that means that it's always just the right concentration. Magic?
Re: New "acid" to remove calcite from specimens
August 10, 2011 11:32AM
Hallo, have someone try the Barracuda on Natrolite or other zeolites? Whith Hcl you get a silica gel .
Thanks.
AngryAngler17
Re: New "acid" to remove calcite from specimens
August 24, 2011 02:08PM
Marc,

Does your company sell urea hydrochoride? I think a lot of people on here were just looking to purchase it and try it out. In light of what you've posted some of us may be swayed away from ordering barracuda.Thanks
Wallace Mitchell
Contact
May 15, 2012 05:57PM
Rory,
I would like to reestablish contact with you.

Wallace
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