From Rowan:
Rowan Softyak DK is a blend of yak, cotton, and nylon in DK weight to give knitters and crocheters the best of all possible worlds: The softness of cashmere with less of the price tag plus added durability and washability in 14 colors. The blend of cotton and yak gives a pretty melange effect as the yak is a darker fibre and thus absorbs the colour differently to the cotton.