As of February 27th, 2023, the Longhorn Quarry is still here. Only things to look out for are the police patrolling nearby parking lots, and active sites to the West of the quarry. I tried parking at a closed business, but scooted when the cops rolled around--I ended up getting permission to park at the nearby gas station, which was nice. Inside the buildings can get pretty dusty, so don't go into rooms full of sediment without a mask like I did, unless you wanna come out coughing like you've got the Pharoah's curse.
Here are the highlights!