There is no Elven Chainmail in BG1. Anywhere. (Not counting any items that may have been added or changed with BGT installed, that is.)
There is indeed a suit of highly enchanted Chainmail, and it is indeed worn by an Elf, but that does
not make it Elven Chainmail.
Characteristics of Elven Chainmail are:
- Does not block the use Thieving skills (although it does cause skill penalties while worn)
- Does not block the casting of Wizard spells
- Can be worn by Thieves (but not by Druids, Wizards, or any kits that forbid metal armor)
The characteristics of the Chainmail in BG1 are as follows:
- Allows Stealth while worn
For
real Elven Chainmail, you've got to wait until BG2.