### "Adamantite" is an AD&D-era name for adamantine

"Adamantite" is the name given to that metal in AD&D, while D&D 3e onward standardly used "adamantine".

"Adamantite" appears in the AD&D 1e _Player's Handbook_ (1978) and _Dungeon Master's Guide_ (1979), where it refers to a metal used to make exceptionally good magical swords and armour. It also appears in the adventure module S1 Tomb of Horrors, also written by Gygax, where a "1-foot-thick adamantite" door blocks progress (p.7), and likewise in S1-4 Realm of Horror (1987).

We see "adamantite" in AD&D 2e, such as the Planescape _Planes of Conflict_ (1995), where adamantite dragons are said to inhabit Bytopia (Liber Benevolentiae, p.43).

However, by D&D 3e, we see "adamantine" replace "adamantite" to describe the same things. As [JohnP noted](https://rpg.stackexchange.com/a/149478/40971), Daern's instant fortress is now made of "adamantine", where in AD&D 1e its material was called "adamantite". Bytopia is now inhabited by the "adamantine dragon" (Dragon #321, p. 44), and the Tomb of Horrors (3e web conversion) says the doors used to be made of adamantine (p.25):

>The 1-foot-thick steel door (it's too expensive for the demons to keep replacing adamantine doors) is suffused with a _globe of invulnerability_ effect.

### Drow connection to "adamantite"

D3 Vault of the Drow features adamantite, a metal which the drow can craft (p.13):

> These creatures dwell in a pool of molten lava at the far end of their smithy, and they make the adamantite alloy and draw the wire.

And:

> Drow wear a fine mesh armor of exquisite workmanship. It is an alloy of steel containing adamantite [...]

> The value of this alloy is that when it is exposed to the strange radiation in the Drow homeland (see MODULE D3, VAULT OF THE DROW) for a period of one month, its magical bonuses come to the fore.

The drow also use poison, but I cannot find any reference to adamantite working differently with poison, except that both drow adamantite armor and drow poison are impaired by being brought to the surface.

In fact, the drow specifically have to re-apply their poison over time:

> Drow sleep poison decays instantly in sunlight. Its power is lost after about 60 days in any event, and the coating on the small bolts and javelins must be periodically renewed with fresh applications of the fungoid substance. The Dark Elves will often have small barrels filled with several packets of this poison, each sealed to insure the poisonous substance remains fresh for about 1 year.