25 Karat Gold?

Guys,

I never thought to ask about this here until now. About a decade ago, there was a cereal box that had some facts about different things, and one of those facts was

"24 Karat Gold is NOT "pure" gold. There is a little bit of copper added to it to give it some strength. True pure gold is so soft, that you can mold it like clay. Wouldn't it be fun to get your hands on some?"

So, if this is true, and copper IS added to 24 karat gold, is absolutely PURE gold called "25" karat gold?

 

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No such thing as 25kt, 24kt is the max at is .999 pure.

 

24 Karat means 24 parts gold and 18 karat typically means 18 parts gold and 6 parts Silver (could also be copper or copper/silver) and so forth.

 

Interesting fact: not all "facts" presented on cereal boxes are actually factual.

 

Then, this cereal box fact lies? I tend to think that, if 24K is only .999 and not 100% pure, then obviously there is a more pure 25K gold. I mean, the only way to turly answer this question is, DO the smelters ADD copper OR silver or both to pure gold to make it 24K? I'm not knocking you guys's answers. Just trying to carry on a conversation here.

 

Is it even possible to get totally pure gold....

 

I assume that 18 carat gold is 75% gold and 25% something else by weight.
Strictly speaking 99% pure gold is really only 23.76 carat.:dead-horse:

 

Sigh.

http://en.wikipedia.org/wiki/Carat_(purity)

 

There you go dragging facts into it again. Sheesh.

 

What we are getting in to here is reality. Can you get any material in 100.0000000000000000000 (tired of hitting the 0) % purity? Can you go above 100% - subject to definition, maybe, but for the discussion here, we need to really deal with 99.9999999999999999999999999999 and so on %, because wherever you end this series of 9's you will round it off to 100.0000 - one less than you had places for 9's. Take a look online at significant figures and that will maybe help. The idea is that the refiners are trying to the best of their ability to make 100% pure gold, but have assayed it and found that the purity is ----. If they cannot detect anything, they could also be admitting the limits of detection of their instruments. In looking at other metals that can be ordered from chemical suppliers you will rarely find anything beyond 99.999%. At this level, any inclusions are impurities rather than alloying materials. Pure gold has a Moh Hardness of 2.5, so it is not like clay.

 

The only way that refiners could be getting .999 gold, is if a large batch of .999 coins/objects were being melted. Gold does not occur in such purity in nature. Most alluvial gold averages about 75-85%. Some gold in quartz deposits (veins) can be higher, but usually less than 90%. To get .999, the gold is often treated with cyanide which separates the gold and then it goes to the smelters, where temperature and fluxes can allow the % to be raised to a higher level. This is why gold and silver at the 90% level was the normal until equipment and assaying jumped ahead.

 

I never rely on information printed on the back of a cereal box.......

Now if it was a 'cracker jacks' box, that would be different.

 

HA HA HA HA HA HA!!! I really laughed at that one. I gotta admit that was a good one. :hail:

 

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I know you know a lot about gemology and minerology Jim, but I beg to differ to an extent. In "King Midas' Gold, Excavations at Sardis", in the excavations of Lydian smelters they found evidence of fairly consistently high purities of gold. The electrum coins they made were intentionally mixed to a consistent level by mixing 96-99% gold with silver to get a standard alloy. 96-99% was achievable by ancients, so I don't think that explains why 90% or similar purity was chosen. Btw most ancient gold was higher than 90% very consistently, further evidence that ancient smelters could achieve well above 90% purity consistently.

 

25 karat gold would be 104.17% pure. (25/24 = 1.041666) I haven't seem much gold over 100% pure. Come to think of it, I haven't seen any 100% pure gold.

 

I am 104.166% sure that there cannot be 104.166% pure gold.

 

I certainly admit I know little about ancient smeltering and even less about the accuracy of their assay methods. However, your post did stimulate me to look through my "ancient " reference books and most only mention the electrum ratio and the weights of various ancient gold coins. Wikipedia has an unreferenced statement that the gold was close to pure, I am sure by now,someone has done a non-destructive analysis of gold% in various coins, although mechanisms more accurate than specific gravity comparisons have only been developed relatively recent. Someplace I read that "alchemy" studies and procedures did pursue extensively mechanisms of "creating " gold as well as separating it chemically so that would be the first step. If you know of any reference stating how they determined the purity of gold used in the ancients, I would be very interested. Thanks for the compliment , but it is just a interest, and not a professional aspect. I highly respect your knowledge of ancients similarly.
Jim

 

There is a subtle distinction here that should be understood. When there is a statement that gold is .999 pure, this doesn't mean it's absolutely .999 pure. It only means that it has been tested or manufactured to be at least this pure. It could be .999999 pure or possibly even 100% pure. They reason is they don't test beyond .999 is because the cost of doing measurements for such minuscule amounts of material isn't worth it for the vast majority of cases.

The Canadian mint sells the .99999 pure gold maple in a special issue assay card. The only reason they do this is to demonstrate their technical abilities as refiners. In other words, it's bragging rights but beyond that, there is no practical purpose of such items. I don't even think these coins even hold up that well on resale. Gold is gold and you don't get any extra for that kind of purity.