Mixture of compounds, mainly abietic acid, C20O2H30
Colophonium is an alcohol soluble resin which is sometimes used as a binder and as a fuel-binder combination . As such it is not used very often since it is expensive and doesn't have much adhesion capacity. Shimizu discerns two different types of colophony. One type is called wood resin and strongly smells of wood or somewhat like an aetheric oil. This is the common resin. Another type he names "combustion agent bl" in some of his books and this is sold as a natural phenolic resin called Vinsol, available at some pyro suppliers.
Artist paint stores often sell colophonium. It is also used by violin players, for the treatment of wooden floors and in the paper industry.
Colophonium is not particularly toxic or dangerous