Butterfly Brooch with Silver Onyx and Marcasite

• Onyx - Onyx is a form of agate, used from antiquity and popular again in the 1920s and 30s. European onyx is generally green, but can be many other colours, and can contain bands of black and/or white.
  
  This multicoloured stone is widely used for table tops, lamp bases and in jewellery. Some types of onyx are also used for cameos of which the upper white layer is cut away to reveal the colour beneath.
• Marcasite - Marcasite is a mineral, iron sulphide, but is rarely used in jewellery. Instead marcasite is the name given to iron pyrites, the mineral sold as marcasite which is identical in copmosition to iron sulphide but crystalises as a cube, making it more suitable for jewellery. It is a brassy yellow in colour and is also known as "fool's gold", and sits well with silver rather than gold becasue of its colour.
  
  Marcasite has been used in jewellery since ancient times and became popular again in jewellery in the 18th century, continuing through to the early 20th century, with the settings becoming cheaper as time progressed, eventually earning the sobriquet "costume jewellery" along with other cheap jewellery that was made for a prevailing pattern and meant to be changed with each new outfit.

This item has been included into following indexes:

• brooches, depicting - butterfly 229
• brooches, set with - marcasite 194
• brooches, silver - silver items 2,532