Or a certain kind of quartz...What exactly does it mean, and why is it important to know about it when choosing a watch? Thanks!
It will increase the frequency of the ions travelling inside the oven. The Quartz crystal will act as an oscillator and will generate the clock pulse required for the operation of oven.
I guess it depends on the frequency of the crystal. If the frequency is close to the wavelength of the microwaves (or a harmonic), the crystal will vibrate in resonance. Being totally bombarded with all that energy, it could crack.
A hot rock? -- Seriously I don't think much would happen to quartz, as microwaves heating rely on dielectric heating for the energy to be transferred into a substance, and (Fused) quartz has quite a low value for it's dielectric constant of 3.75 at 20 °C 1 MHz, might be higher at difference frequencies. Might heat up a bit, but I don't think it'll get THAT warm. But then there's the question of what would happen to the unabsorbed microwave radiation.I think most would be absorbed by the microwaves case (heating it up) but I suspect theres an increased risk of burning out the magnetron -- If the crystal is in a metal can, then you WILL probably get sparks/heating- dielectric constant of Aluminium at (1 kHz) =1300
