Allotropes are the physical forms of a chemical element that occurs in the same physical state with varying physical properties but comparable chemical properties.
Diamond and graphite are the two most popular allotropes of carbon, but they are crystalline in nature.
Amorphous forms of carbon are: Coke, Coal, Charcoal (or wood charcoal), Lampblack, Animal charcoal (or bone black), Carbon black, Petroleum coke, Gas carbon are amorphous forms of carbon.