QUARTZ: UNUSUAL PROPERTIES

EPS2 Students: This will not be covered in examinations

Some unusual properties arise from the absence of a center of symmetry in quartz (and tourmaline):

QUARTZ DOES NOT HAVE A center OF SYMMETRY!

  • The c crystallographic axis is perpendicular to the long axis of uncut crystals. If the crystal had a center of symmetry, the two ends of these crystals would ha ve identical properties. However, this is not present. Consequently:

    applic ation of mechanical stress (e.g., compression) along this axis causes charges of opposite sign at each end (piezoelectricity);

    conversely, applied electrical fields produce mechanical stresses.

    The piezoelectric property makes quartz valuable in pressure gauges, electronic frequency control devices, radios, and other applications.

  • Because no symmetry planes are parallel to the c axis, crystals may develop either a left handed or right handed configuration; in nature, the characteristics of left and right handedness occur approximately equally.