Limestone Quarry (Location)
A megafortress in the Haureris Nome.
As with all such installations, scan carefully to guard against unexpected hostiles. There are two treasures in the commander's tent on the upper level, one in the quarry cave, and one by the rebel prisoners.
Ignore the secret passage and instead just enter through the break in the spike wall, in the northeast corner of camp.
Once inside, kill your way south along the top of the gate wall.
Finish by taking the southeast east watchtower, but don't ride the zipline down. Instead, drop down into the camp- one of the captains' bunks is directly below you.
Drop into the bushes, and kill him in his sleep.
Climb up the wall again- not all the way, and sneak west to the crane.
You can take this one, then the next one, as a direct path to the west wall. You can also trap the brazier on the way
Snipe the west wall sentry as you get close, then complete the transit, and turn left, heading straight for the commander.
Kill him in his chair, and loot the carbon crystal from his desk.
Go deeper into this quarter, and loot the white chest there.
Come back out, and drop down the northside of this platform, You should able to see the last captain's sleeping place.
Drop down and make his sleep a little more permanent.
Now head north, bearing left for the quarry cave.
Smash the westmost wooden wall here, and loot the red chest behind it.
Emerge, and look both ways before crossing the road east. When clear, scamper up the rock to get a vantage on the prison area guard.
Smash another wooden panel for the final treasure.
Taking it completes the location.
You're also in the perfect place to free the prisoners, if you so choose.