[HangnJudge]

Piezoelectric phenomenon?

[NormsRevenge]

Yup.. piezoelectric effect, quartz when compressed or stressed can cause a discharge, sounds similar to a St Elmo like event

[Figment]

“Piezoelectric phenomenon?”

I think that is basically what it is. I heard about this from relatives who were in a large one around Eureka CA around 1980

[backwoods-engineer]

Almost certainly a piezoelectric or triboelectric phenomenon.