Chemical Composition：Hydrocarbons with traces of minerals
Crystal System：Amorphous, Organic Material
Hardness：2.5 - 4
Locality：Whitby (England), China, France, Mongolia, New Mexio, Siberia and Spain
Remarks：It's a form of fossilized wood, Aged: around 180 million years ago.
Jet is found in two forms, hard and soft. Hard jet is the result of the carbon compression and salt water; soft jet is the result of the carbon compression and fresh water.
Their appearance is relatively the same, but soft jet is a good deal more brittle and fragile than hard.
Whitby - Hard
Spain, France and North America - Soft
How it formed:
The wood was originally buried in the muddy sediment on the sea floor or within stagnant swamps.
Jet is formed within sedimentary rocks, by the long-term effects of increased temperature in oxygen-depleted conditions.
Jets from these different localities have slightly different properties and Whitby is a specific form of jet derived from weed which is a relative of todays monkey puzzle tree (araucaria araucana).
The history of Jet traces the development of prehistoric man from as early as the Stone Age and has continued to be more or less significant up to the present day.
During the Roman regins, jet was quite popular as a magic stone. It was used in jewelry and said to protect one from the "evil eye."
During Victorian times it was used mainly for jewelry, also lead to the rise of the price.