Zenimax posted an article which features questions submitted by the community, answered by the developers. The article focuses on Crafting, and whilst it does not necessarily provide any new information, it’s a good read for anyone who isn’t up to date with the crafting system in Elder Scrolls Online.
The article confirms that every type of crafting material can be found in the overland world of Tamriel – you don’t need to run dungeons or defeat special bosses to get your hands on rare crafting materials.