Rank
Description
Approximate Carbon content
100
Anthracite
95-93%
200
Low volatile steam coal
93-91.5%
300
Prime coking coal
90.5-89
400
"
89-87
500
Coking /gas coal
87-85
600
85-84.5
700
General purpose coal
84.5-83.5
800
High Volatile steam
83.5-81.5
900
and house coal
81.5-80
