2.15" Polished Agate Skull with Amethyst Crown

Amethyst is a purple variety of quartz (SiO2) that owes its violet color to natural gamma irradiation, iron impurities, and the presence of trace elements, which result in complex crystal lattice substitutions. It is considered a semi-precious gemstone, and just two centuries ago was considered to have a value on par with diamonds, sapphires, and rubies. The largest and best known amethyst deposits occur in southern Brazil and Uruguay, where they are found in hydrothermally-formed geodes, but many localities around the world produce an amazing variety of amethyst crystals and formations. They are almost always formed in medium- to high-temperature geological settings.

About Agate

Agate is a variety of microcrystalline quartz (chalcedony) that displays translucence and, in some cases, banding. Agate primarily forms when silica-rich fluids fill pockets within rocks and/or fossils, depositing the silica along the walls of the rock. This process can result in banding patterns, as the compositions and impurities of these depositing fluids change over time. These banding patterns can either form as flat layers, creating linear patterns known as waterline agate, or as rounded layers, forming more common ring-like patterns. These patterns depend on the surfaces available for deposition.