If you can, post a pic of it. Are there any other rocks with shiny things in them?
When an electric current is passed thru a quartz crystal, there is a tiny vibration caused. This vibration occurs at a known, predictable and constant rate, or frequency. This frequency is then used to callibrate the intervals that the clock records (by the movement of its hands, or a change in its digital display) as seconds.
Quartz watches work by counting the vibrations of a quartz crystal which vibrates at (I think) about 34000 cycles per second. So once the counter has reached 34000 then one second has passed. The counter is the reset to begin counting the next second. The key point is that if the count varies slightly - say 34002- the error in the length of the second is negligible.
Quartz has a constant resonant frequency when an electric charge is sent through it. With such consistency it is relatively easy to set up a gear situation to take adavantage of it, resulting in remarkably accurate timepieces.
The crystal vibrates at a precise frequency, a frequency detector is tuned to a certain frequency and displays any detected differences as a function of tracking time.
The quartz crystal works kind of like a spring. when you apply an electric field to it, it bends. Just like putting a mass on a spring, it bounces at a particular frequency. You can use the oscillations to count how long it takes for something to happen and make a clock out of it.
