Subtly Included Quartz
A transparent quartz crystal with just a couple of very subtle inclusions.
Although quartz occurs in a wide variety of colours, in its purest form it's colourless and transparent.
When quartz is subjected to pressure it releases an electrical charge. Correctly known as piezoelectricity, this phenomenon was first discovered in 1880.
'Piezoelectricity' comes from the Greek 'piezein' meaning 'to squeeze' or 'press'.
The vibration produced is similar to the the way crystal glasses ring when tapped. Ironically glass referred to as crystal is not crystalline at all. It's simply glass with lead added to it which is why it's often called lead crystal.
When looking through this transparent crystal it acts as a prism. When white light passes through the quartz the light bends. This optical phenomenon is known as refraction.
White light (an example being daylight) is made up of several different colours. Each one bends at a slightly different speed as it passes from one medium into the next.
As a result they all come out the other side of the prism separately instead of combined. For refraction of light to take place light must hit the crystal at an angle as opposed to head-on.
If you work at a computer hold this quartz crystal horizontally and look through it at your screen. If necessary rotate it slightly and you'll see refraction of light.
