Developments of the Rayleigh equation: “Crystal” a Pascal program for simulating fractional crystallization

n interactive program to simulate the fractional crystallization process has been implemented. The Pascal program, termed ''Crystal'', uses an equation based on the trace elements of the parent and daughter magmas. ''Crystal'' is based on the development of the Rayleigh equation: C(l)/C(o)=(1 - SIGMAy(i))(SIGMAy(i)K(i)/SIGMAy(i)-1) where the new variable y, represents the mass of phase i in the solid in relation to the initial mass. From this form of the equation, it is possible to determine the mass fraction of phase i in the solid x(i) without assigning a series of arbitrary values to x(i) or F (residual melt fraction). At the present time, using in a stochastic manner the Rayleigh equation, one or other of the equation variables has to be assigned arbitrarily by balancing the mass with the major elements. The main advantage of the method is that it prevents external factors from conditioning the trace-element model.