The three-meter tall amethyst geode - a hollow rock filled with amethyst crystals - is the main attraction at the Crystal Caves at Atherton, southwest of Cairns. But it's now missing a bit after a ...

Amethyst is a violet variety of quartz that 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 ...

Large crystals found in geodes and other rocks are relatively rare ... and emeralds continue to qualify as "precious." (At one time, amethyst was also considered a precious gem, but large reserves ...