File:The Quarterly journal of the Geological Society of London (13205846445).jpg

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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,