Mineral foundations are usually marketed along with a complex set of brushes, but in reality you only need two brushes: one for the overall application and another one for a mineral concealer.

A kabuki brush is by far the best tool to achieve natural, even results. It has a stump of a handle and a dome-shaped, fluffy, thick head. The original kabuki by Bare Escentuals is so far the best. Watch out for brushes that have a narrow and pointed head - they cannot spread the mineral powder flawlessly. Read more of this post