This mitten was made from handspun wool yarn, and then felted. It is extremely warm. If the wool had been oilier, it would probably be waterproof too.
This is a close-up of part of the palm of the mitten. The rows of stitches are visible, running diagonally across the image. (I didn't say it was a good close-up!) The apparent twisting is due to the plied yarn rather than any characteristic of the stitch I used.