Anodized Aluminum or Gold Plated

[Geo]

hmm, smells like gold, taste like gold. :lol: looks good to me. place that small amount of foil in something small like a test tube and dissolve it in hcl/Cl and test the solution with stannous.

 

[niteliteone]

Kind of looks like gold foils to me :twisted:
Goes to show how it is always best to "test" any material you suspect might contain PM's, as even skilled eyes here said their was no PM's, just by looking at the pictures.

 

[g_axelsson]

I don't want to write "I told you so!" and brag a bit... oops, I just did! :mrgreen:

Congratulations, now to the fun part, how are you going to get the gold off the aluminum?
At least it looks to be quite thick, it didn't fall apart in small flakes.

Göran

 

[Harold_V]

Al does not oxidize,

Sorry, but you're very wrong. Not only does aluminum oxidize, it does so rapidly, at ambient temperatures. That's one of the problems that must be overcome when welding aluminum. It is addressed by using AC and high frequency. The aluminum is also prepared by applying a stainless brush, to remove the oxide coating that is quite common.

Are you familiar with grinding wheels? The vast majority you'll find in life are made of aluminum oxide.

Harold

 

[Harold_V]

i may have a biased location because of all the aerospace companies located nearby but i have had quite a few gold plated parts that defied rational thinking as to why and functionality. thats why i say test to be sure.

Your advice was spot on. Readers need to learn that testing is critical to success in refining.
Don't judge things using what you might consider to be good logic. Let me explain.

It is generally assumed that gold plating is never applied heavily. That is true even when gold was selling for $35/ounce. However, it's not true. Many years ago I was asked to process a large amount of scrap plated military items, all from what was reputed to be microwave. I intended to strip with cyanide, but I was not aware at that time of the addition of an oxidizer, so I had issues with the gold perforating, then the cyanide attacking the base metal. At that point gold recovery slowed to a halt, although the vast majority of the gold had been stripped.

I do not recall the exact yield for these plated parts, but they rivaled gold filled material. The guy had at least a couple hundred pounds of the stuff. I was not satisfied with the process I had chosen, so I put the project on the back burner, in preparation for running the material in a sulfuric stripping cell. He grew short of patience and requested the material be returned, so I never processed the rest.

Sure, it's not common to find gold in volume, and not common to find aluminum gold plated, but that doesn't mean it's impossible. Keep an open mind, setting your expectations low. If you happen to discover a find that goes against the rules, you'll be pleasantly surprised instead of being constantly disappointed when you think everything you see is gold.

Had a real funny experience about ten years after I had started refining. I was to meet a couple in a public place, because they had a large ingot of gold that they wanted to liquidate. Needless to say, I was skeptical.

We met in a restaurant, where they promptly pulled out a large bar that had a corner removed. To my trained eye, it was obvious that there was no gold present, that what I was seeing was a bar of common yellow brass. A test with nitric proved my hunch to be correct. (For the record, I carried a test kit with me at all times when conducting business away from my lab).

What these people had was a bar that had been stolen from a display, although they never made it clear from where it was taken. I was in the company of crooks, who didn't trust anyone (why should they? They couldn't be trusted, otherwise they wouldn't have had possession of a stolen "ingot").

Harold

 

[bswartzwelder]

Glad to hear you found some gold. I do not trust pictures to convey something as critical as to whether an item has gold plating on it or not.

I have several digital cameras and two of them are supposed to be of good quality. I, cannot get a good clear sharp picture of anything at close range with them. Pictures taken from a distance are usually always very clear and sharp, but close ups are just not possible. It's because of the focal length of the camera. Most cameras have a focal length of about 3 feet to infinity and that works just fine for most photography. Lately, I have found that if I step back, and then use the "zoom" feature I can get a fair picture. Then I "photo shop" it and crop the edges down to a manageable size. However, by doing this, I lose some of the clarity.

Just curious what everyone else is using for the nice close photos they post?

 

[nivrnb]

Just curious what everyone else is using for the nice close photos they post?

I was just using me phone camera for the shots on this post. But I found something interesting on the internet posted below.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=19361

 

[a_bab]

Well, I have to excuse myself for not believing that Al can be gold plated. It's the first time I see it. Seing is believing...
I never seen anything then computer related Al heat spreaders, and in this area they are always anodized.

Harold, I'm perfectly aware Al does oxidize in the atmosphere. What I wanted to say is that it does not do it like iron for instance: that is, in a humid enviroment Al would resist better then copper for instance. I've seen heavily coroded pieces of Al, but this only occures in harsh enviroments, or in contact with iron/copper under water/high humidity (anodic protection).

 

[Woodworker1997]

Al does not oxidize,

Sorry, but you're very wrong. Not only does aluminum oxidize, it does so rapidly, at ambient temperatures. That's one of the problems that must be overcome when welding aluminum. It is addressed by using AC and high frequency. The aluminum is also prepared by applying a stainless brush, to remove the oxide coating that is quite common.

Are you familiar with grinding wheels? The vast majority you'll find in life are made of aluminum oxide.

Harold

All of the cast Al under the hood of my Tacoma agrees with you Harold. It all has white oxide all over it.

Derek

 

[nivrnb]

Just some photo updates.

Didn't do a good job rinsing the pieces.

 

[bigjohn]

Just my 2 cents but those foils look to thick to be gold plating. If that is gold, Thats one nice find :lol:

 

[a_bab]

It's not just gold; probably gold plated Cu/Ni.

I've seen copper plated Al used in electrical wires.

 

[butcher]

It looks like a fish to me. :lol:

 

[g_axelsson]

It looks like there are some copper left on the gold foil, then there probably is nickel with the gold.

Do you have any nitric acid? This would be perfect material for dissolving the thin copper+nickel layer under the gold without dissolving the aluminum.

Göran

 

[Anonymous]

Is it just my eyes or does it look like an extremely thin layer of plating?

 

[Geo]

not necessarily. if the parts were made when gold was relatively cheap, and especially if it was originally aerospace or military, it could be much thicker than, say RF shielding.

 

[nivrnb]

All,

Just wanted to post some great threads on this subject, so I could go back and read.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=19177&p=194083&hilit=thick+gold+plating#p194083

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=12129&p=119372&hilit=thick+gold+plating#p119372

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=10106

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=42&t=8578&p=80245&hilit=thick+gold+plating#p80245

 

[kyle95]

However If you have access to a furnace and crucible you could melt it down with borax and silica and it will separate