Tests are carried out with suspensions of fibrous chrysotile particles and nickel sulphide ore containing chrysotile as a gangue. They corroborate published results, and indicate a very strong effect of particle shape on slurry rheology. Such suspensions exhibit time dependent properties. The flotation tests revealed that the viscosity of this system strongly affects flotation performance. At a solids concentration of 15-20% (w/w), the concentrate yield increases and the concentrate grade dramatically declines. This deterioration is observed when the Casson yield stress exceeds 1.5-2 Pa. The tests imply that the rheological properties of the investigated system are mainly determined by fibrous components. However, because of the presence of anisotropic mineral particles, the effect of particle-particle interactions cannot be separated from the effect of particle shape in this system.