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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 14, 



Organic Structure and Mineral Composition of the Coal. 



The coal of Eastern Virginia, although derived from a different 

 vegetation from that of the ancient carhoniferous period, resembles 

 very closely the older coal in structure, appearance and composition. 

 That of the Blackheath mine has usually a highly resinous lustre and 

 conchoidal fracture, and always contains at least as large a proportion 

 of gaseous or volatile ingredients (hydrogen, oxygen and nitrogen) as 

 the coal of the palaeozoic rocks of the United States. 



The coal is also divided into horizontal layers of slight thickness 

 parallel to the planes of stratification, as in the older kind of coal. 

 Sometimes these layers consist alternately of highly crystalline and 

 resinous coal with a bright lustre, and of other portions exactly re- 

 sembling charcoal in appearance. The same is observed in some of 

 our Welsh coal, where the charcoal is called "mother coal." 



My friend Dr. Hooker has had the kindness to examine for me 

 some specimens of this Virginian charcoal, which I procured at the 

 Blackheath mines, and others from those of Clover-hill before alluded 

 to, and he finds vegetable structure in both, but appearing in each 

 locality to belong to a different species of plant. At first he thought 

 they might be referable to ferns, but abandoned that opinion from 

 the total absence of cellular and scalariform tissues. The prominent 

 glands of the fibres are much more minute than the glands of coni- 

 ferous tissue, whilst the large perforated tubes are foreign to that 

 order. They depart still more widely from Zamia, and do not indeed 

 present any obvious affinity with any existing natural order. "Both 

 are very opake, much crushed, and so fragile that it is difficult to 

 obtain fragments fit for microscopic investigation. They principally 

 consist of a mass of parallel fibres or elongated cells, amongst which 

 occur very large tubes whose walls are pierced with circular, or lon- 

 gitudinally or transversely elongated holes, either scattered or placed 

 very close together. 



Vegetable Structure of Mineral Charcoal from Clover-hill Mines, 



Fig. 3. 



