Anyone know the purity of copper gold and where it’s found?
Hi…copper can be an impurity in natural gold…and rose gold sold at jewelers is an alloy of gold and copper, but it is hard to find pure copper in alluvial systems as it oxidizes quickly. The percentage of copper impurity in alluvial gold is low an is alongside other impurity’s like silver and lead, mercury etc…the amount of impurity’s gives you the carat(ct) of the gold, 9ct gold contains 37.5% gold and18ct gold contains 75% pure gold etc. The percentage of impurity’s in natural gold can vary depending where it is found.
thanks Lepresean, I found a peice the other day cleaning out a crack and Brian looked at it and said it was copper gold.
I recall years ago reading one of Tony Nolans books it was about 87% gold but didn’t really know much about the stuff.
I know my Grandmother’s jewellery used to include copper gold bracelets.
Impurities in gold can be all over the place. There is no hard & fast percentage but certain areas have their gold signature with the impurities being very much the same. The gold buyers back in the day got to know these percentages & just payed the miners for gold from those areas based on what they knew those percentages to be.
The savvy miner would tell the gold buyer that his gold was from so & so area, which was a higher gold purity, to get a better price for his hard won gold. The gold buyers developed a good eye & could generally pick by the look & colour where the gold had come from.
A lot of the gold in the Coromandel has a high silver content & so a very dull gold colour diluted down by the silver. The “gold” bars produced at the Martha Mine in Waihi are silver in colour due to this fact. 80-90 % silver, 10-20% gold. A lot of the gold in the Coromandel is called electrum gold, also due to this fact. In the early days of mining in the Coro a lot of the mines struggled to pay there way as the silver was worth bugger all & the recovery processes they had in those early days, they were losing a heap of gold in the waste. Which they knew from assays but on a commercial recovery scale they didn’t have the technology to combat the impurities that was robbing their gold.
I have found coppery gold in the Arrow & Cardrona areas detecting. What % I don’t know. But a very different darker coppery gold colour.
JW 
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Thanks for the info. kiwijw. I was told the stuff I found was around 80%
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