From Halopedia, the Halo wiki
This Unidentified BXR titanium mine was one of the many mining facilities on Reach.
This mine, located in the Viery Territory, was built near a massive meteor crater to take advantage of the exposed titanium there. During the Fall of Reach, a SPARTAN team was sent to defend the mine from Covenant forces, but was eventually wiped out.
Unearthed, a Firefight map that is part of the Defiant Map Pack, is set here.
Concept art of the mine.
Another concept art piece, depicting the mining operations in the crater.
A panorama of the facility.
A general view of the facility.