VX 7 nerve gas
From Halopedia, the Halo wiki
Canisters containing the nerve gas were strewn throughout New Mombasa during the Covenant's attack on the city. The UNSC In Amber Clad had a stock of VX 7 canisters and seemingly deployed some to the surface of Installation 05. Jiralhanae forces captured some of the gas and likely planned to use it against the humans.
The same crate seen above in Halo 2: Anniversary.
List of appearances
- Halo 2 (First appearance)