Proposed Standard Conventions for Expressing the Elastic and Piezoelectric Properties of Right and Left Quartz

Three sources of confusion in the literature on quartz crystals have recently been pointed out:
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the distinction between right and left quartz, the conventions respecting the positive directions of the crystal axes, and conventions respecting the signs of angles when the axial system is rotated. After further consideration of this subject in the present paper, it is recommended that writers employ only that definition of right and left quartz which is now generally accepted, and that uniform conventions be agreed upon for axial directions and rotations. Voigt's usage in the main is advocated with this important exception: it is proposed that a right-handed system of axes be used for right quartz, left-handed for left quartz. This arrangement may appropriately be called the Right-Left axial system. The advantages are that all elastic and piezoelectric constants then retain the same sign for both types of crystal, and that all equations having to do with rotated axes apply equally to both types. No heed need be given to the distinction between right and left quartz except when angles are to be laid off on an actual specimen, and then the difference lies only in the reversal of the x axis for left quartz. A table showing the conventions used by various authors is included