Geometrical classification of conjugate vein arrays

A classification of conjugate vein arrays is proposed on the basis of three angular parameters that can be readily measured at outcrops. Relationships amongst these parameters imply that geometry of conjugate vein arrays varies within a continuous spectrum limited by three end-members. triangular plot is devised for representation of conjugate vein arrays, and its application is substantiated by several published and new examples. Evidence from overprinting relationships and consistency in the orientations of principal stresses imply that different types of conjugate vein arrays can develop in a common stress system.