Whitby Jet was a favorite for mourning jewelry…

..  in the Victorian era.  Jet is a product of high pressure decomposition of wood from and ancient type of coniferous tree millions of years ago.  It is found in hard form which is the result of carbon compression and salt water.  Soft jet is the result of carbon compression and fresh water.

(Raw Whitby Jet and an 1860’s stick pin carved from it)