A new way for obtaining material for professions has been introduced in Mists of Pandaria.
Motes of Harmony drop throughout all Pandaria and once you have 10, you get a 1x Spirit of Harmony that can be exchanged for mats depending on your profession needs, in Valley of Eternal Blossoms.
Here is a list of all the items that can be purchased, the vendor has two tabs and covers every material needed for professions.
Spirit Dust is needed for enchanting, Ghost Iron Ore, obviously mining, Golden Lotus for Alchemy, Starlight ink for inscription and so on.
Kyparite is used in blacksmithing, exotic leather in leatherworking and Serpent's eye in jewelcrafting.
Here's the icon of the Mote in an inventory. It's soulbound and you can clearly see its tooltip and icon. In the second screenshot, there's Spirit of Harmony.
But Spirit of Harmony works not only as a core crafting ingredient, but it can be also used to purchase a variety of additional bonuses or materials that your character may need. While not every profession will get equal value of them, most everyone will need to collect them for one reason or another.
Here are some examples of the many ways that Spirit of Harmony can be used:
Alchemy: Purchase an extra Transmute.
Archaeology: Purchase a restored artifact.
Cooking: Exchange for an Iron Paw Token.
Engineering: New mounts and personal goggles.
Herbalism: Purchase Herbs.
Inscription: Purchase rare inks.
Jewelcrafting: Use to purchase extra daily discoveries.
Tailoring/Blacksmithing/Leatherworking: Used to create epic items.