Section of an amethyst geode from South Africa. This rough piece of rock lined with small terminated crystals makes an outstanding display piece. We have it standing on a small plate stand which is not included.
Amethyst which is a variety of the mineral quartz is coloured by impurities of iron. Iron alone however does not cause the quartz crystals to change colour. In its purest form quartz is colourless and whilst impurities in the crystal structure do bring about a change in colour, for that to happen it needs to be exposed to heat. In nature that's often done through radiation but heating amethyst in the oven will have the same effect.
Most of the world's commercial grade citrine is heated amethyst because natural citrine is quite rare hence also expensive. It is quite easy to identify heated amethyst from natural citrine because the shade of colour and the way it's dispersed within the crystal is quite different.
Birthstone for the month of February amethyst is widely used for lapidary purposes and geodes of all sizes are always in great demand. Care must be taken where amethyst is positioned because bright sunlight will over time cause the colour to fade.
This amethyst geode was carefully chosen during one of our many trips to South Africa.