Acronym and details:
Group: thermoplastic
Developed: moulding technology from early 17th century
Trade names:
Manufacturing process: compression moulding; thermoforming
Cost: medium
Colour: natural horn colour, typically dyed black; also imitations of tortoiseshell
Transparency: translucent or opaque
Rigidity: rigid but when thin flexes
Feel: sometimes textured
Smell: none
Other: fibrous texture sometimes visible
Typical uses: drinking vessels; buttons; combs; imitation jet jewellery; snuff boxes; cutlery handles; small translucent panels used e.g. in windows and lanterns
Degradation: stress cracks; some distortion and shrinkage but otherwise stable