Elemental Earth

Elemental Earth is a fundamental building block of the world. It embodies the virtues of strength and protection. Because of these qualities, it is sought after by crafters to create powerful new items.

Source
Elemental Earth drops off of various earth-based creatures in Azeroth.

As a quest objective
Elemental Mastery (quest)

As an ingredient
Elemental Earth is used in the following recipes:

Alchemy

 * Greater Nature Protection Potion
 * Restorative Potion

Blacksmithing

 * Glinting Steel Dagger
 * Elemental Sharpening Stone
 * Orcish War Leggings

Enchanting

 * Lesser Elemental Slayer

Engineering

 * Goblin Mining Helmet
 * Truesilver Transformer

Leatherworking

 * Earthen Leather Shoulders
 * Heavy Earthen Gloves
 * Frost Leather Cloak
 * Gloves of the Greatfather

Tailoring

 * Earthen Vest
 * Earthen Silk Belt
 * Robe of Power

Jewelcrafting

 * The Jade Eye