Jade

Jade is a raw gem. It is naturally rich with life and color, making it the perfect raw material for animating companions from the stone.

In Pandaria, jade is used to build a single massive statue for the August Celestial Yu'lon, so that she can reincarnate through them around every 300 years.

Source
This item can be found in Gold Veins, Tin Veins and Iron Deposits everywhere. It is also a reward from the quest Find Agmond. It is also dropped from the elite mobs in Dun Modr. (As of patch 2.3, the elite tag has been removed from Dun Modr mobs.)

Prospecting Tin Ore (low chance) or Iron Ore can also yield Jade.

As an ingredient
Jade is used in the following recipes:

Blacksmithing

 * Frost Tiger Blade
 * Golden Scale Cuirass
 * Green Iron Hauberk
 * Jade Serpentblade
 * The Shatterer

Engineering

 * Accurate Scope
 * Discombobulator Ray
 * Gnomish Battle Chicken
 * Gnomish Cloaking Device
 * Gnomish Shrink Ray
 * Green Lens

Jewelcrafting

 * Golden Dragon Ring
 * Jade Pendant of Blasting
 * The Jade Eye
 * Golden Ring of Power
 * Figurine - Jade Owl

Leatherworking

 * Gem-Studded Leather Belt
 * Ironfeather Breastplate
 * Ironfeather Shoulders

Tailoring

 * Dreamweave Circlet

As a quest objective

 * Items of Power: Jade (1)