Traces of iron are responsible for the characteristic violet coloration of the quartz variety known as amethyst. However, how the geodes can grow to this size has remained a mystery. Most geodes ...
Amethyst is a violet variety of quartz which has been used as a gemstone for many centuries and is a key economic resource in northern Uruguay. Geodes are hollow rock formations often with quartz ...
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.
Amethyst, the violet variety of quartz, has been used as a gemstone for centuries and is a key economic resource in northern Uruguay. Geodes are hollow rock formations often with quartz crystals, such ...