Tomb of Khafre (Location)
A pyramid tomb in Giza.
Head downpassage until there's a drop. Go forward to loot that modest room, then turn back. Where there was a drop before, you'll find a downward passage under the passage you entered by. Which is to say, just keep going downhill, until you reach a 'dead end' room with a scarab wall.
Head down to find a boat lever.
Push the rack under the far end to transform it into a ramp, and leap to the upper level.
Once up, hop back across the beams to loot the box at the base of the seated statue- it's a carbon crystal.
When you've got it, proceed forward into the tablet room, where you can pick up some loot and complete the location.
As ever, you can fast travel out now, but exiting through the back way will yield some extra loot.