A new equilibrium form of zircon crystal

The surface tensions of the {100}, {110}, {101} and {211} faces are calculated by using Machenzie's method. A new equilibrium form of zircon crystal is then derived on the basis of Wulf's Law. This theoretic form consists of {100} prismatic faces and {211} pyramidal faces, which is different from that of the prediction by the periodic bond chain theory. The discovery of the equilibrium form of zircon crystal provides a clue for understanding of the morphology of zircon crystals formed in deep magma chamber, indicating that zircon morphology is an indicator of crystallization conditions.