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How do I uncover the copper color in native copper nuggets?

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I want the copper color for some art pieces.  I found the nuggets at the Caledonia mine in Upper Michigan.  I would like to remove the patina/coating so the copper parts stand out from the other minerals in the samples.  The copper segments are very irregular and pointed, so they can't be scrubbed without breaking.
asked Jul 10, 2016 by Jgasper (120 points)

2 Answers

0 votes
There are many ways. Just using lemon juice and salt will allow you to clean it and it is non-toxic.
answered Jul 12, 2016 by Weasel (58,930 points)
0 votes

If you're only trying to remove the dark tarnish from the native copper (and leave it shiny like a new penny), one of the best things to use is a product called "Copper Dip" (it used to be called "Copper Brite").  It transforms the native copper almost instantly and with no scrubbing (all you have to do is rinse it off).  It's a dry granular acid mix you hydrate yourself -- I make it in a one gallon plastic milk container.  You can get it in very large amounts from lapidary supply houses.  One of the places that carries it in more affordable amounts is Keweenaw Gem and Gift in Houghton, Michigan (in the UP).  They sell it in amounts that can make up to one gallon for around $8.50.   You can order it over the phone at 800-554-8447 and they'll mail it to you.

answered Mar 11, 2017 by drdjmiller