On the Piezoelectric Properties of Tourmaline

Oscillating piezoelectric plates of different frequencies have been made from California and South African tourmaline. These plates have a frequency response of approximately 3770 kc per millimeter of thickness. The temperature coefficient for both to be negative and is about 25.5 parts per million per degree centigrade for the African specimen and 28.1 parts per million per degree centigrade for the California crystal. Comparison of the tourmaline plates with a Y-cut quartz plate of the same size and frequency shows the tourmaline oscillators decidedly inferior on the basis of power output