Extended Data Fig. 1: The crystallography of quartz and related piezoelectric effects.
From: Gold nugget formation from earthquake-induced piezoelectricity in quartz
The crystal planes of quartz and the piezoelectric response when distorted. (a) Crystallography of left- and right- handed quartz. The basal {c}, prismatic {m} and rhombohedral {r, z} planes are indicated. Minor planes, such as bipyramidal and acute rhombohedral, are not shown. (b) Quartz crystal viewed parallel to the c-axis. Here, the first- {m} and second- order {a} prismatic planes can be easily distinguished. (c) The effect of an applied mechanical stress (parallel to X) on the quartz atomic framework (top left and right). As the framework is distorted (top right), a piezoelectric potential is generated. When a quartz crystal is viewed parallel to the c-axis (bottom left and right) the distribution of positive (red) and negative (blue) piezoelectric charge can be recognised. (d) Note that only the {a} crystal planes are piezoelectric in quartz.
