Black Rock Quarry Restricted Area. When doing the quarry mission find black rock for Dr Marshall I stumbled upon a hidden location with sniper HISS guys and weird colored rocks that seemed to kill me via radiation or something. Your destination is located in the Maintenance Sector - this is a Restricted Area shown in the picture above.
Black Rock Quarry Furnace Chamber. Use Levitate to climb the platforms and then follow the sewers until you find a door that leads you back to the Furnace Chamber. There is this large door with an elevator behind in the quarry.
Just before reaching the main part of the quarry turn.
Black Rock Quarry Furnace Chamber. Darling Dimensional Staffing Correspondence. Youll find yourself in a restricted area of the Black Stone quarry. This document is in the control room of the Cable Cart in the Restricted Area north of the quarry.