Amethyst crystals are hexagonal and can occur as tall prismatic crystals or short stubby ones. The crystals often have horizontal striations on their sides or faces. The transparent prismatic crystals can be found in clusters in an incrustation (rock cavity). This lining of crystals is also known as a druse and in a nodular stone is commonly called a geode.
The Antonia Minor teapot in lapis lazuli, gilt silver and enameled gold. The bust on the handle is of Roman antiquity, carved during the life of Antonia Minor (36 BC-37 AD), mother to Emperor Claudius and grandmother to Emperor Caligula -while everything below the string of pearls, which hides the join, was created and carved by Dionysio, Prague, c1652 (KHM, Vienna)