Chemical Forums

Specialty Chemistry Forums => Citizen Chemist => Topic started by: SteveE on August 03, 2020, 07:18:57 AM

Title: Dissolving Calcite
Post by: SteveE on August 03, 2020, 07:18:57 AM

Hello Everyone

Years ago I was a gold nugget prospector in Arizona and Nevada. I found a lot of gold back in those days.

I still have a gold in Calcite specimen I'd like to extract the gold from since the spot price is so high.

It's a 3 ounce Calcite specimen containing 1 ounce of gold. Could someone please tell me how much HCL  acid it would require to dissolve the remaining 2 ounces of Calcite? I don't want to buy any more acid than I need to.

Any help will be appreciated.

Thanks

Title: Re: Dissolving Calcite With Gold Specimen
Post by: SteveE on August 03, 2020, 07:33:59 AM

Also, I would be using 37% HCL acid which is readily available in hardware stores.

Title: Re: Dissolving Calcite
Post by: Borek on August 03, 2020, 09:50:25 AM

I strongly doubt you will be able to buy just enough acid, most bottles I have ever seen contain several times more than you need.

Title: Re: Dissolving Calcite
Post by: AWK on August 03, 2020, 10:06:23 AM

If it is actually calcite, then about 15 ml of 4-5% vinegar per gram of calcite will suffice.

Title: Re: Dissolving Calcite
Post by: SteveE on August 03, 2020, 10:15:26 AM

Quote from: AWK on August 03, 2020, 10:06:23 AM

If it is actually calcite, then about 15 ml of 4-5% vinegar per gram of calcite will suffice.

I tried dissolving it in vinegar but takes too long. That's why I wanted to know how much 37% hydrochloric acid it would take. Should work faster.

Title: Re: Dissolving Calcite
Post by: AWK on August 03, 2020, 10:18:48 AM

You may boil the solution.

Title: Re: Dissolving Calcite
Post by: SteveE on August 03, 2020, 07:02:31 PM

Thanks. I'll try that.

Title: Re: Dissolving Calcite
Post by: AWK on August 04, 2020, 03:59:49 AM

The gold in ores is often accompanied by barite and quartz. Hydrochloric acid will not dissolve these minerals. Then the only solution is to dissolve the gold and precipitate it by reduction.

Title: Re: Dissolving Calcite
Post by: SteveE on August 04, 2020, 07:38:01 AM

You mean dissolving in aqua regia? If so, what would you use to precipitate the gold out with?

Title: Re: Dissolving Calcite
Post by: AWK on August 04, 2020, 12:20:00 PM

Zinc dust.