Nodrassil, Mount Hyjal
A great place to put those mining skills to use is at the Mount Jyjal inn. Just outside the initial quest staging zone of the inn, there are countess numbers of Scalding Rock Elementals. These Elementals are fighting the guards and are easy pickings. The guards will help you kill them, but once killed they can be looted and then mined. When you use your mining skill on the Scalding Rock Elemental corpse, they have a chance to produce 1-2 Volatile Earths. The greys that come from both looting and mining their corpses will pile up fast, but can easily be sold right back inside the inn.
Elemental Goo is one of the Horde daily quests that can be randomly selected as the daily for all jewelcrafters. On days that the selected quest is Elemental Goo, this same area mentioned above becomes much more exciting and profitable. The Jewelcrafting daily quest required the jewelers to loot 10 quest drop items from any Cataclysm elementals. These elementals are the closest and easiest elementals near Orgrimmar. There will be a lot of jewelcrafters coming to kill their 15-20 mobs for the 10 quest drops that will fly or portal right back to town. They leave the corpses of the elementals scattered everywhere. All you need to do is run up and down the kill lines and mine the corpses before they despawn.
The Scalding Rock Elementals also drop Lovely Charms during the Love Is In the Air in game holiday.