i think a great way to get up quarry is to find harvestable mobs, saves you the trouble of running around looking for nodes. Thy use quarry on dead whirlwinds, golems, rockdervish etc. I'd try CiS and prolly dungeon area in Kaon's Rush
There's a cave in Skrillen point that has an infinite loop of sandstone. Though it does have mobs in it, so if you're in your mid20's adventuring, it might not be worth it to you. If you're a higher level toon, though, it'd be great. They aren't very hard to kill if you need to get rid of them though.
For sandstone, go to Forest's Heart - in the northwest corner of the zone, where the mountains come down to the river's edge, there's a bunch of level 25/26 2-dot rock elementals. Same ones used for URT quest The Ambassador's Daughter. Respawn is fast enough that even if you're having someone else kill them so you're constantly harvesting you can't run out.
Go to CIS and head to the area that has a ton of spiders to the North (I believe) of the camp with the quest givers. That'll get you all the sandstone you need if I remember properly.
