From Ancient Times Agate is a mined microcrystalline form of quartz and, like jasper, part of the chalcedony mineral class. The gemstone comes in a wide range of colors and patterns, but dendritic ...

A royal slice of agate has gone on display at the Museum. The piece of agate, a type of chalcedony which itself is a variety of quartz, has a pattern resulting from different impurities such as iron ...