By using the seed crystals of designed profiles so that inward as well as outward growth may take place with respect to the z axis, various growth forms of synthetic quartz are displayed. The formations of three different types of trigonal tripezohedron, i.e. the vicinal of 5161, 6155 and the closed pair of triangular facets deformed from 2112 and 10559 are described. Direct evidences are given, demonstrating that during the lateral progression across z (0001) plane, the-x direction will overtake that of + x.The general sequence of growth rate of different faces including + x≥ - x is explained in terms of the duly proposed concept of interface molecular group waviness. In addition to the acuity of the molecular reentrant angles upon z(0001), the more widely opened and therefore more readily fitted lateral reentrant angles formed during the lateral movement of the growth front along the negative polar directions enhances the rate of progression.The reentrant angles of the growing molecules, projected on certain chosen reference axial plane, will act as a measure of the interface molecular group waviness. A hybrid series of interface types are classified, in which the degree of flatness of the molecular group waviness will determine the degree of "flatness" of the interface, while the share of "stepness" and "kinkness" is estimated by resolving the normal of the oriented interface into the directions of the diad and triad axes of the crystal respectively.The assumed statistically dominant form of the molecules in the supersaturated hydrothermal solution is ring shaped Si6O6(OH)12 with the least specific surface free energy, being a relatively more stable metastable stage, appear to be the more appropriate growth units. In accordance with the structure of the crystal and the orientation of the growing interface, the growing molecules will be oriented to adopt the maximum possible molecular reentrant angles so as to minimise the interfacial free energy. This basic assumption explains why growth on the prism faces is likely to be very slow.The polarization of molecules and adsorption of foreign ions on the growing polar faces and also the possible grouping of the ring shaped molecules before crystallization are finally discussed.
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