The Mix texture mixes two textures together. By default, a float value controls the Amount. A value of 0 means the First Texture is visible, and a value of 1 means the Second Texture is visible. Values in-between blend the two textures together in a linear fashion. The Mix texture is similar to the Cosine Mix texture, except for the behavior of the mix slider.
Figure 1: A blue color is mixed with a Marble texture, and the mix amount is controlled by a Sine Wave texture