Raw Quartz, Its Imperfections and Inspection

Q UARTZ is one of the commonest of crystalline minerals and occurs in many variations of size, color, purity, and structural perfection. It is used for such varied purposes as jewelry, fusing into heat and chemical resistant dishes, and for optical and piezoelectric units. However, the following discussion will be concerned mainly with such raw quartz as is commercially used in the manufacture of piezoelectric circuit elements. It might be added that the terminology used may be more in keeping with the language of the piezoelectric manufacturers than of the geologist. Further, description of many unusual types of defects, and variations of common types has been omitted. An attempt is here made to describe such defects as are of most interest in the piezoelectric art and in such a manner as to be most widely useful. Following is a description of raw quartz and its defects, the means of observing these defects, their appearance as recorded photographically, and a discussion of their effects on finished plates. The words defects and imperfections as used in this article mean a deviation from a perfect specimen of raw quartz; they do not necessarily mean that the material is not entirely satisfactory for the purposes intended. 4 . 2 SOURCE, SIZE, SHAPE