In article ,
Richard J Kinch wrote:

Don Bruder writes:

If it's a quartz based sand, rather than the more usual "silica
sand", that might go a long way toward explaining it, since quartz does
do the piezoelectric thing.

Uh, silica IS quartz.

Actually, by my understanding, quartz is indeed a form of silica, but
the reverse isn't necessarily true. For piezo to be involved, the
crystal structure is important, and not all forms of silica have the
right structure. Silica in the form of quartz has the right structure.
Silica in most of its other forms doesn't.

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