I tossed together a little dual-hcmos inverter crystal oscillator yesterday to use as a marker generator while trying to tune a receiver. At one point I put an old HC-6 (ie, big) 1 mhz crystal in it. One of the leads was broken off short, so it was kind of wedged up against another component lead temporarily, in a way that let me key the oscillator off and on easily.
It sparked! Tiny blue flash at the intermittent connection.
Not totally unreasonable given that piezo crystals are used to do that intentionally in grill ignitors.
Suprising thing though is that the 74hc04 does not appear to have died. When it's not making sparks it oscillates about as I'd expect.