BITUMINOUS COALS 197 



the components the whole mass is fairly well preserved and then 

 again, components are met with in which the whole mass is dis- 

 organized and consists of irregular fragments, but always of the 

 same color and general appearance. Frequently the component 

 is composed of bands of more or less well-preserved tissues alternat- 

 ing with bands of disorganized, granular matter. 



The components vary largely in size as seen under the micro- 

 scope, ranging from but tiny bits to good-sized masses. There is 

 also a wide range of transparency in them, both in different com- 

 ponents and in different parts of the same component. The most 

 transparent ones are of a dark-brown color in thin section, but 

 opaque in medium-thick sections. 



This component, possibly derived from bark, is characteristic 

 through its brownish red color in thin section, irregular structure, 

 lumpiness, and relative opacity, and is easily distinguishable from 

 the rest of the coal. Although in some layers or laminae it may be 

 quite abundant, yet, on the whole, it forms but a small part of coal. 



The aUritus. — It has been shown that the larger anthraxylon 

 components or bands of bright coal are embedded in the dull coal; 

 and in turn that the dull coal consists largely of smaller anthraxylon 

 constituents together with a few other constituents such as cuticles 

 and barklike constituents, embedded in a general matrix, the 

 attritus. 



At low magnification, the attritus appears as a uniformly 

 granular, amorphous mass (Figs. 2, 7, and 10). At a higher magni- 

 fication, it at once appears as a very heterogeneous substance. 

 Typical appearances of the attritus in cross-section are shown at 

 d-2 and d-4. (Fig. 11) ; dld-i, d-2,, and d-'j (Fig. 19) ; at d-i, d-^,, and 

 d-^ (Fig. 20); and in horizontal section in Figures 22, 24, and 

 .25. A close examination at a high magnification will at once 

 reveal that it is composed of a number of groups or classes of con- 

 stituents, most of the riiembers of which are specifically and 

 definitely definable and their origin determinable. These are 

 cellulosic degradation products or humic matter, spore-exines, 

 resinous matter, cuticular matter, more highly carbonized matter, 

 certain small bodies usually designated as rodlets or needles, and 

 some mineral matter. 



