rang

CONT: Le rang d'un charbon est le degré de houillification atteint par celui-ci au cours de sa maturation géologique. On dira par exemple, que tel charbon est d'un rang élevé.
OBS: rang : terme normalisé par l'ISO.

CONT: In the United States, the standard ranks of coal include lignite, subbituminous coal, bituminous coal, and anthracite and are based on fixed carbon, volatile matter, heating value, and agglomerating (or caking) properties.
OBS: The term ""rank"" refers to the stage of carbonification reached in the course of metamorphism. (In international usage the term ""type"" is sometimes given the meaning commonly given to rank in North America and in much of the world).