Jet is a species of bituminous coal (cannel coal) which can be cut with a knife. The hardness is 1 to 2.5; specific gravity, 1.35; its lustre is not very high, and color pitch-black.
It is found in England, France, Hesse, Spain, Italy, and Prussia.
Amber.
Amber is a fossil, and is not to be classed amongst minerals, but this material has always been used as an ornament, and a few notes will not be out of place here.
This vegetable fossil, which has been known to the world for ages, the Greeks called electron.
It is very light, having a specific gravity of 1.065 to 1.08, and is 2 to 2.5 in hardness.
The principal color is yellow, in various shades, sometimes running into white or reddish-brown and black.
Amber is transparent to translucent, possesses single refraction, a resinous lustre to a high degree, becomes electric by rubbing, and burns readily before the blow-pipe.
Amber when heated becomes soft and pliable.
Amber is composed of: