I thought adamantium buffs might like this little piece of Greek history:

"Forthwith Kratos and Bia caused Prometheus to stand upright against a huge pillar of rock, and they held up his arms above his head while Haphaetus bound him to the pillar by the neck wrist and ankles, riveting his fetters to the rock with nails of adamant."

Then Haphaetus says to Prometheus, "....Alas! that my skill is put to such a proof- that I must bind one of race divine in these shackles which no power can break"

Yes and if you read gensis closely in the right version the sword the blocks the way into eden is also made of adamantium.

It's not made from adamantium, it's made from adamant, not the same thing.

From my apple's dictionary widget:

Origin: Old English (as a noun), from old French adamaunt , via Latin from Greek adamas, adamant, 'untamable, invincible' (later used to denote the hardest metal or stone, hence diamond), from a- 'not' + daman 'to tame'.  The phrase 'to be adamant' comes from the 1930s, although adjectival use has been implied in such works as "an adamant heart" since the 16th century.

Note that the definition is not just for something that is hard or unyielding, but also 'untamable'.  An adjective that describes Wolverine quite well; he is both hard-headed and wild.

The adamant from the greek quote above might actually describe diamond rather than a metal, a substance which would easily be the hardest and most unyielding to greek knowledge.

In any case adamant / adamantium same difference tomatoe/ tomato is found in certain versions of the Bible and several other books of note. Though the refrences are few and far between they usually are discriptive of certian artifacts and or people. Oddly enough I have found refrence in 23 books of historic Myth or Religion and it is not only in Latin based languages but in middle asian and african texts as well though I grant the 3 refrences of it in Africa I have found are speaking of (Friend Spiders webing).

If you look Admanas is Babylonian in origion not old english and is referenced in the Torah and Koran in refrence to Solomons sword hilt and his wisdom. 

Your definision is accurate and yoiur observation is also very keen and I apreciate that we have more than one scholar here on the site. Being well read should not mean only of the classics or only of the comic orientation.