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Horn of Africa Copper and Ammonia Reaction

Posted by Eamon Allstone  
Horn of Africa Copper and Ammonia Reaction
March 13, 2012 03:47PM


Hi

I put a small piece of these in Ammonium Hydroxide 0.88 it turned the Ammonia & the sample.a dark blue fast.

As they are so small i have not been able to work up the SG any suggestions on a method?

They scratch 99.8% copper tube but not a stainless steel knife blade,

The streak is green from the green part and brown from the brown.

Slightly attracted to a 12x12mm N52 magnet when floated in a small plastic tub in water are pulled along

What other tests should I preform to help identity.

Eamon
avatar Re: Horn of Africa Copper and Ammonia Reaction
March 14, 2012 03:54PM
Hello Eamon,

You might put a small green crystal in either dilute hydrochloric acid or white vinegar to see if it bubbles or dissolves. If so you have malachite. (there are also a lot of other possibilities). I think the brown material is probalbly "limonite", which is a mixture of mostly hydrous iron oxides. The slight magnetism might indicate a very small amount of magnetite in the limonite. is the streak definitely brown or a yellowish brown, or a reddish brown?
Copper and Vinegar Reaction
March 15, 2012 11:32PM
Hi Donald

I dropped a small picce in white wine vinigar 6% acidity, this moring did not notice any bubbling or reaction,

Left it in it returned 3 hours later the find that vinigar had turned green and now 12hrs later it appears to be the same size.

The Streak of the "limonite" is a reddish brown.

I worked up an average SG 3.1 from 5.3g dry.

I would like to know what it is and also learn how to indentify minerials.

Eamon
avatar Re: Horn of Africa Copper and Ammonia Reaction
March 16, 2012 03:30PM
Hello Eamon,

If the streak from the brownish mineral is a reddish brown, you probably have mostly hematite in it. I doubt that it is pure hematite and suspect other hydrous iron oxides in there also. The slight magnetism would indicate perhaps a small amount of magnetite. If the green mineral did not bubble it is probably not malachite. But has to be soluble in acid. There are more than two dozen possibilities. Running it down is a bit of a problem in chemistry. As to the Specific Gravity, at best it indicates that you have mostly light minerals. When one has a mixture of minerals, as you do, there is not much that the S. G. can tell you.

Don
avatar Re: Horn of Africa Copper and Ammonia Reaction
May 26, 2012 04:10AM
de    
The green colour of the acid is due to copper ions, which tells us that the copper bearing mineral (or one of them, in case we have a mixture) is soluble in acetic acid. This is important information as it excludes most copper silicates.
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