Do tumbled quartz have piezoelectric properties?
Yes, all quartz has piezoelectric properties, whether it has
been tumbled or not. However, in natural quartz, were optical
twinning (equally distributed left and right quartz forms inside
the material) is very common, the piezoelectric effect is not
strong. That is the main reason why only synthetic quartz is being
used by manufacturers, where twinning is almost absent.