hmm.. well if you're serious then:
Thottbot: World of Warcraft or
Allakhazam.com has the quests listed and it shows the right locations on map aswell..
basically you'll find the crystal by just heading directly east from auberdine, it's on the slopes of the mountain range between darkshore and felwood->
http://www.thottbot.com/?m=2552&s=b it's the yellow box that has white circle around it