Black Rock Quarry Control. Continue until you reach the next elevator leading this time to the excavation site. Theres also the Black Rock Quarry to which we can get using the Sector Elevator down to the Maintenance Sector Access Corridor then through the NSC Control Room and on to.
Enter the door leading to the Black Rock Quarry. Once you reach the elevator going to the quarry you will notice it is broken. In the Black Rock Quarry Entrance where the Astral monster is is a door in an above alcove you can enter.
There will be a forklift resting against a wall.
Once you reach the bottom you will be in the Black Rock Quarry area. There are two control points at Black Rock Quarry - one at the entrance and the second one you only unlock later in the main mission. Head down to the bottom to unlock the hidden location. The Quarry Threshold also known as the Black Rock Quarry is a Threshold located in the Maintenance Sector of the Oldest HouseThe Federal Bureau of Control uses the quarry to mine for Black Rock a material highly valuable to them due to its ability to negate paranatural effects.