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How malleable is platinum and rhodium

SAG 180

Titanium
Joined
Sep 17, 2007
Location
Cairns, Qld, Australia
I know guy who has 5Kgs of something heavy his dead Grandfather had said was platinum. Whatever these small grey pellets are they smash when hit by a hammer and won't melt with an oxy. I suggested he measure the specific gravity and suggested it may be tungsten carbide. Anyone know how platinum or rhodium handles, are they malleable?.
 
Platinum is hard but quite ductile, rhodium would never be called ductile, it takes much effort to form it. Tungsten carbide isn't in the ductile camp either. Oxy-acetylene will melt platinum.

When you say "smash" does that mean they flatten out or turn to granules or powder?

Platinum is a widely used catalyst and commonly bound to ceramic pellets. The platinum content is a very small percentage by weight.

If the fellow has 5 Kg of metallic platinum or rhodium he's walking in tall sweet grass.
 
I dunno.
My guess is whatever they were, the amount of platinum used was very small. So what you are seeing as being smashed is the other components that make up the original device.
I doubt the whole pile is all platinum, just traces of it within.
 
I dunno.
My guess is whatever they were, the amount of platinum used was very small. So what you are seeing as being smashed is the other components that make up the original device.
I doubt the whole pile is all platinum, just traces of it within.

Here's a pic they are 1/8" dia. apparently they shatter but the guy didn't say how much. Most modern phone exchange relays I've ever seen were rhodium plated silver. I just hope they aren't something nasty like cobalt 60. Five kilos of rhodium would be worth about $400 000, not a bad gift for cleaning out granddad's shed.

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If the parts are old relay contacts, they could be sintered platinum, and hence crumbly under the hammer.

Even if it is just tantalum, it is seriously valuable

platinum, tantalum and tungsten have a density of 18 times water, but tantalum and tungsten will react with strong acids, and will oxidise at red heat, tungsten giving a yellowish oxide, platinum will only react with aqua regia (nitric and hydrochloric acids, freshly mixed) and does not oxidise at red heat in air.
 
Platinum is a superb relay contact material. Palladium and platinum were used pre-WWII in telephone switching relays. Don't mess around, this stash could be very valuable.
 
If the parts are old relay contacts, they could be sintered platinum, and hence crumbly under the hammer.

Even if it is just tantalum, it is seriously valuable

platinum, tantalum and tungsten have a density of 18 times water, but tantalum and tungsten will react with strong acids, and will oxidise at red heat, tungsten giving a yellowish oxide, platinum will only react with aqua regia (nitric and hydrochloric acids, freshly mixed) and does not oxidise at red heat in air.

That's a few more things to try out with them. Keep in mind he's unable to melt them with an oxy torch which does suggest a ceramic as platinum will easily melt with oxy. He's also mention he sent a sample to a metal refiner: "It's totally worthless stuff but feel free to leave it here and we'll dispose of it for you".

Platinum is a superb relay contact material. Palladium and platinum were used pre-WWII in telephone switching relays. Don't mess around, this stash could be very valuable.

I didn't think of palladium, anyway hopefully he'll be able to measure the S.G. and come up with a density for the material which is quite dense. He would be well advised to send out some more samples for testing to refiners.
 
If you know anyone at a university that has access to a scanning electron microscope or x-ray diffration equipment they would likely be able to tell you what it is quite easily. I would be glad to do it for you, but I doubt you want to be sending it half way around the world.
 
i have an x-ray material anaylizer here at the shop. If you want to stick one in an envelope and mail it to me I will shoot it and tell you what the chemistry is. PM me if you want and I will give you my address.
 
If these are Platinum they are worth between U.S.$250,000 and U.S.$300,000 . Unfortunately from the discription it is unlikly that they are pure platinum. Un the other hand if they are prewar they probably are not some form of ceramic. Most likly some form of sintered alloy. But even if they are an alloy with only one percent platinum that would be close to 3 grand so it would definitly be worth getting an analysis done. For a quick refrence you might see if any of the scrap metal dealers near you have an metal test gun that they would check your sample with. These guns have become quite common at scrap yards in the last couple years and can test a sample in a matter of seconds
 
The colors on my monitor may be off, but to me, those pellets look like copper tungsten.

I love threads like this. Please let us know if you find out what they are.
 
Platinum wire was used under ceramic glaze in the 1920s as a cheap alternative to filligree silver, although it was harder to draw than silver, it had the added advantage of not blackening if the kiln atmosphere contained sulphur.

I've heard stories from old guys about people buying scrap metal after the war and sitting clipping platinum contacts out, and extracting platinum from aero engine spark plugs.
 
If you know anyone at a university that has access to a scanning electron microscope or x-ray diffration equipment they would likely be able to tell you what it is quite easily. I would be glad to do it for you, but I doubt you want to be sending it half way around the world.


Jwatts, I know my local university had a brand spanking new Xray diffractometer and an Xray fluoroscope as well as some kind of Xray analyser attached to the JEOL electron microscope. I actually ran the lab for a very short time, more as a place holder shortly before it was closed down.

Kingbob: I'll pass this guys email on to you so he can send a pellet.

Thanks for all the help guys.
 
I spent a lot of hours running an old JEOL SEM. It didn't have all the bells and whistles that some of the newer scopes do, but it was kinda fun to operate for some reason. I think it was all the knobs and switches.
 








 
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