Commodity Code

coal

http://resource.geosciml.org/classifier/cgi/commodity-code/coal

definition Coal is a combustible black or brownish-black sedimentary rock composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen, derived from fossilized organic remains. Coal is subdivided in terms of rank. The hardest form or highest rank is anthracite coal, which can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Intermediate rank coal is bituminous and low rank coal includes lignite. more like this
narrower anthracite
broader coal
black coal
broader coal
brown coal
broader coal
notation
01.01.05.01.01 more like this
Coal more like this
source http://en.wikipedia.org/wiki/Coal more like this
type
Resource
Concept
broader carbonaceous material
narrower coal
in scheme commodity code
is primary topic of coal