Put a piezo rock in each hand and rub them hard against each other in a small dark room (never a closet) or outside in total darkness. You will see light and sparks within the rocks and at the point of impact. This same rocks will generate an electric voltage when squeezed and deformed. The piezoelectric effect is used for battery-less electric ignition, lets us keep accurate time with quartz watches, very fine focusing eye equipment, generation of instant high voltage and sound amplification/detection equipment. CAUTION: Be careful to keep the rocks away from your eyes when rubbing them together as small bits of rock may fly off! A website said Wintergreen Lifesavers lightup when smashed as well.
The standard deformation of about 0.1% of the original dimension finds use with some potters and industrial chemist as quartz, Rochelle salt, lead titanate zirconate ceramics (e.g. PZT-4, PZT-5A, etc.), barium titanate, and polyvinylidene flouride (a polymer film). One can now buy all sorts of detectors, amplifiers and piezo electricity producing sheeting at: http://www.piezo.com/.
Imagine, musicians, a box of rocks for an amplifier! No Plug! Check it out! Piezoelectricity was "discovered" by Jacques and Pierre Curie in the 1880's during experiments on quartz. While a crystal was depressed a current flowed in one direction. When it was released the current flowed back in the other direction. They discovered that a tap on a severally depressed crystal (flattened) could make it springs back into its original shape instantly (pop up). This tap on the crystal produces one very tiny AC current cycle ~ crystal size and tap size would make more amps per tap/cycle. For example, you could sit in your small dark room (never a closet) with your new found 2 piezo electric rocks, hook each one up an insulated copper electric wire, hook each wire to a terminal of a small flash lite bulb and rub your rocks! The bulb will light if you got good rocks and rub hard but then, again, why do need the bulb if the rocks light up!
It's basically a stretch within the bonds of the atoms that end up polarizing them that makes it happen and not an external friction. One can grow very find piezo electric generators quite easily. The supersaturation method of growing crystals is the fastest way ~ Rochelle Salt and Alum heated together with adding a whole bunch of both and then let cool. The slower evaporative method is where you just mix salt and alum, as much as will dissolve. Then let sit about a week or so under non-humid conditions. These are generally of better clarity and shape. One can peck on these with a stick and create around a 12 volt battery flow. Check out:
I'm sure everyone is aware of Nicola Tesla (Westinghouse, AC power, radio, sonar, lazers, etc.) who in the1890's tried to transmit electrical power without wires and at high altitudes through the soil and air. He set up an experiment on Pikes Peak to send a radio signal from Pikes Peak to Paris, France. Tesla thought that when lightning struck the ground it set up powerful waves that moved from one side of the earth to the other doing lots of energy work and changes~ that Earth, herself, the great conductor. Tesla said he could transmit unlimited amounts of power to any place on earth with virtually no loss. He is the only human to ever produce lightning creating bolts more than a hundred feet in length. The experiment burned out the dynamo at the El Paso Electric Company and the entire city lost power. He did light up his vacuum tubes 12 miles away and Paris did pick up an "R". He had sent out Marquinn, his Mother's name! The depression happened.
Another interesting electrical rock is fulgurite. These are long hollow rock shafts that are produced in wet sands by lightning strikes. They are very electrically conductive and could be hooked to your new piezo electric rocks just as the insulated electric wires for making a circuit. Great wand stems. And guess where is the lightning capital of the world that produces the largest and most beautiful fulgurites on Earth ~ Clay County, Florida! Many are piezo electric.
Some folks ask, "So how do they differ from magnets?". All early magnets came from loadstones/lodestones and these come from a rock called magnetite when it's struck by lightning. Both lodestone and magnetite are the exact same mineral form of iron(III) oxide Fe3O4 ~ being one of several iron oxides but not like rust. Iron, steel and ordinary magnetite are attracted to a magnetic field, including the Earth's magnetic field. Only magnetite with this particular energized crystalline structure (lodestone) could act as a magnet and attract (and magnetize) iron in the ancient world ~ and was magical! The direction pointing nature of lodestone was 1st known by the ancient matriarchal Greeks women near Magnesiaas (sailors), by the 4th century in China for geomancy and by the 12th century the Chinese as a compass in navigation. And even far earlier Magnetotactic bacteria, who build miniature magnets inside themselves, were used. They establish their orientation relative to the Earth's magnetic field like a compass and float on water.
Magnets work by the fact that little electrons are usually sitting on one atom going round and a round and round that one little proton (positive center) and staying all balanced energy wise. Well, in magnets those little electrons are migrating round and a round the length of the hole piece ~ not just their own Moma nucleus. This creates a pull on the electrons in some iron based metals like iron Fe(II). It's like they just wanna go party together! Called "excitement" technically!
I find all this especially interesting in that bones produce piezo electricity naturally as does alotta little centers in alotta those little systems in us. It seems first there's a piezo electric source for a charge and then that this is surrounded by some small magnetic field surrounded/protected by a little larger magnetic field surrounded by some little larger magnetic field ~ some of these are the transport systems for nutrients and air happening in blood or bone! Circles, little circles in circles in circles. Circles all in us. Much research is currently being done trying to prove piezo is the source for the Christian "laying on" of hands, prayer, love energy field work and "New Age" healing. Are we walking ancient lightning strikes that can exzood love from our bones? I'm just so completely glad all our acupuncturist and nutritionist are getting into all these crazy micro-electrical devices that work on a cellular level with all these very small electrical charges. What if it is all about the source and that the smaller these charges are, the deeper they work on a cellular level ~ with polarity being set by the source piezo electric charge. But then what do I know? I can't even understand with all this stored lightning energy in the ground (piezo and magnetic), Florida sunshine (solar) and our own backs (uah!) why we need oil companies controlling our government and lives?