Chalcedony JewelryWhere the name comes from: Greek chalcedon, Latin chalcedonius, Middle English calcedonie - precious stone. A catch-all term that can be applied to many forms of quartz, many semi-precious gemstones are forms of chalcedony.
Where the stones come from: Worldwide.
Chemistry: Silicon dioxide, SiO2
Colors: Any and all depending on the inclusion of a wide range of minerals, spotting, banding, stripes etc. are also common.
...and another thing: One of the earliest materials used by mankind as it can be worked to give a razor edge.