Natural jet is the fossilized wood of a tree similar to the monkey-puzzle tree which grew around 180 million years ago. Fossilisation occurred when the trees died and decayed in wet conditions, and layers of dead organisms, debris and mud built up on top, creating great pressure and a build up of heat. Most jet was formed under sea water but a softer form was created in fresh water.  When water levels dropped or the sea level rose due to geological changes, jet could be found in small seams only 20-25cm thick and about a metre long.

Jet has been mined and used for jewellery and small decorative items for over 4000 years, originating from Turkey, Germany, Spain, France and England. It is a very light substance, intense black colour, and is warm to touch. It can be polished beautifully.Today, hard jet is still found in England and Spain, but no mining is allowed and only pieces obtained through beach combing can be used. Softer jet, which is much harder to carve and polish, is found in Russia, New Mexico, China and the Ukraine.

Pre-historic jet jewellery has been found in Switzerland, South Germany and Belgium and Bronze Age pieces in barrows in the UK. The Romans used jet from England and Turkey. In the Middle Ages, jet was used primarily for crosses and rosaries, as well as hairpins, medallions and bracelets.

Victorian Whitby jet snake bracelet

Whitby, in North Yorkshire, was the centre of jet jewellery making in the UK since pre-historic times but it was not until the early 19th century that it really developed as a major industry with significant jet mining being undertaken. The introduction of the railway led to Whitby becoming a seaside resort in the mid 1800s and jet souvenirs were popular. At the same time, the move from the lighter Regency clothing to the heavier crinoline and fuller clothing meant that larger pieces of jewellery could be worn and light jet jewellery was ideal for this. As well, mourning customs, for women in particular, became much stricter. Widows were required to mourn their husband for two and a half to three years, with the first stage of mourning, one year, requiring women to wear complete outfits in black, layered with black crape, including head veils. The second stage, which lasted six months, still required all black outfits but the layers of crape could be removed. For the third stage of the mourning period, women could wear grey, mauves and purple.  Jet jewellery became essential.

Victorian jet brooch

Part II continues next week