The many alchemical alloys of adamantine

Disclaimer 1: if you are a member of the adventuring party known as the geneva convention mild spoilers ahead.

disclaimer 2: i run a completely homebrew setting and know remarkably very little actual WOTC official content. idk if there is something like this, if there is id like to know but please be respectful.

Hey all, so in my campaign ive decided to homebrew around the mechanics of adamantine, making it an (albeit rare) naturally occurring metal and changing its properties from defense against crits. Instead it can provide immunity to different levels of magical attacks depending on the armour (ie 1st level spells for chain mail, 3rd from plate armour) and is comedically more heavy than anything else. Another facet of this is that im allowing adamantine to be alloyed with a myriad of other things to replace the spell resistance trait for another ability. here are the examples i have already:

Adamdrake: adamantine mixed with dragon scales provides the crafted item to channel draconic magic with power/ stability parallel to the amount of chromatic/metallic scales used.

Sky adam: An alloy of different astral plane chunks to the adamantine allows it to create magical force projections (such as the chain of an adamantine meteor). The projection differs depending on the shape that the metal is made.

Arourum alloy: A mixture of tin and cold iron to the adamantine greatly diminishes its strength but allows it to remember the form it is forged into and repair itself to said form on contact.

Evidently there are not very many variations of these alloys so im asking here if anyone has any ideas for these that they would like to share i would love to hear them!!!