User @Poutnik has recently answered two questions(here and here) in which he/she quoted this statement from Wikipedia:

Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum.

I am not sure about the validity of this statement as I found contradicting results regarding iron and platinum amalgams. There has been discussion around iron amalgams on internet giving inconclusive theories about why iron cannot form amalgams (See this reddit post for context) and on further research, I came to know that iron indeed form amalgams albeit unstable (See here). This has also been discussed in a previous question here at chem.SE . User @DrMoishePippik has pointed out that iron can form mercury-based alloys(amalgams?) at specific conditions. So, there is a contradiction regarding formation of iron amalgams.

Some searching also proves that platinum can also form amalgams. From here:

Platinum Amalgam is obtained by trituration of platinum sponge with mercury in a warm mortar; it cannot be obtained by direct union of platinum foil and mercury.

The amalgam has a silvery appearance, and with 12 per cent, of platinum is soft and greasy to the touch, but higher percentages of platinum increase its stiffness. When heated strongly the mercury is volatilised and platinum remains as a grey residue.[...]

But what about the rest two metals, tungsten and tantalum? Does they really not form amalgams? Google search is giving me irrelevant informations. The only thing I found out relevant is that as they do not form amalgams, they can be separated from a mixture of metals using zinc amalgam.

So, the questions are:

  • Does tantalum and tungsted really not form amalgams?
  • If yes, what is the reason? Is it because of the same reason for iron not forming amalgam?
  • If no, is there any evidence/scientific papers to prove it?

I just saw a comment User @Mithoron has left in the question "Why does mercury not form amalgam with iron?"

Pt, W and Ta also resist dissolution with Hg

Is this statement true?

  • 2
    $\begingroup$ Interesting question. The ASM Alloy Database does not even have an entry for Hg-Ta, strongly suggesting that it has not been studied much if at all. It does have Hg-Ti, and the phases there are quite different from, say, Ag-Hg which does suggest there may be difficulties forming an amalgam. $\endgroup$ – Jon Custer Jul 3 '19 at 12:56
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    $\begingroup$ It's also interesting that the metals concerned melt at rather high temperatures: 3290 K for Ta, 3695 K ​for W. Whatever is holding those metallic crystals together isn't letting much Hg sneak in. $\endgroup$ – DrMoishe Pippik Jul 3 '19 at 22:24

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