**Basic Ternary Phase Diagram**

This Demonstration shows two representations of a ternary phase diagram, which is used to represent the phase behavior of three-component mixtures. The black point, which can be moved to any location within the triangle by clicking on that location, represents the composition of the mixture, and each corner of the triangle is a pure component. The mass fraction of a component in the mixture is read off the axis that is the same color as that component in the standard view. These axes are labeled by drawing a line through the point; this line is parallel to the base of the triangle that is opposite the corner corresponding to that pure component. In the alternate representation, the mass fraction of a component is determined by drawing a line through the point and perpendicular to the base opposite that component. The fraction of the distance from the base to the corner is the mass fraction of that component. Ternary phase diagrams can also be drawn using mole fractions instead of mass fractions.