Optical Evolution of Exinite Euring Coalification Based on the Discovery of the Anisotropical Exinite

Having studied the detailed coal petrological characteristics of more than 300 polished coal blocks sampled from eleven coalfields in China the authors have discovered a kind of organic maceral in coals with a high reflectance and strong anisotropy. Some of it conserves clearly the appearance and structure of exinite.According to the original maceral which is changed into anisotropic exinite. it can be divided into six types: anisotropic alginite. anisotropic sporinite. anisotropic cutinite. anisotropic exsudatmite. anisotropic bituminite and anixotropic liptodetrinitc. furthermore there is an amorphous anisotropic matter in coals. Anisotropic exinite is formed gradually by some of exinite during the coalifieation.ft occurs first in flame coal stage, and distributes frequently in coals with rank higher than gas coal stage. The statistics show that the content of anisotropic exinite in coals investigated varies from zero to 1.8%. and that the total content of anisotropic matter in coals is less than 12.74%. commonly from 1.0 to 4.0%. which is much less than that of exinite in specimens sampled from the same coal and the similar coal petrological type, but different coal rank. Since the changing of coal- forming environments and the difference of coal- forming plants, the exinite of same type may have different characteristics.The fluorescent intnsity and reflectance of exinite is the mark of its thermal activities, which will control its evolution processes and final products during the coalirlcation.On the bases of these facts, therefore, the exinite can be grouped into three types according to their optical evolution during the coahfication: l.Thc exinite of extreme thermal activity, such as fluorinite. terpenite and so on. evolutes completely into hydrocarbons. 2.The exinite of large thermal activity, such as some of alginite, resinite, sporinite, cutinite and so on, change into the anisotropic exinite as they draining off the liquid hydrocarbon. 3.And the exinite with less thermal activity shares gradually the same optical properties with intergrowth vitrinite during the coalification.