Black Rock Quarry Hidden Location. You can also look here for some answers. Go through the woods and head to the door leading to the Blackrock Quarry.
On the table next to the TV you will find access card 5. Black Rock Quarry Furnace Chamber. In the room just past the Black Quarry Entrance Control Point the one where all the monsters and Hiss attack you is a doorway located above everything to the left.
Hidden Location 7 Black Rock Quarry 326 When you first enter the Quarry look for a path to your left seeming blocked by large cubes.
Then head downwards and be mindful of mold enemies. Black Rock Quarry Hidden Location. Theres an entry point in the top right. Use Levitate to access this area and follow the sewers to reach a door that leads to the Furnace Chamber.