Tall Freestanding Quartz Crystal
This clear quartz crystal has been shaped as a terminated point. It's beautifully included and from certain angles exhibits small rainbows of colour caused by iridescence.
Iridescence in clear quartz is caused by the interference of light as it passes through the crystal. The interference can produce a range of colours including shades of blue, green, purple and red. The strength of the iridescence depends on the inclusions within the quartz.
Inclusions in minerals are made up of fine layers arranged in such a way that light interferes with itself as it passes through. When light hits the inclusion some is reflected and some is absorbed.
With inclusion being made up of thin layers there's an upper and lower surface. The interference as light reflects off the two surfaces causes iridescence.
Iridescence may also be caused by other factors such as the presence of impurities or defects within the crystal structure. In clear quartz however it's usually caused by the interference of light.
This tall clear quartz terminated point has a vitreous lustre. This is sometimes described as a glass-like finish. It does have the tiniest chip on one side of the point that can be felt more than it can be seen. For this reason is has been slightly reduced.
