Figure 13. Photograph and photomicrographs of Pennsylvanian
bituminous coal. A, Photograph of a lump of bituminous coal from
Pennsylvania showing typical banding caused by layering of a
variety of preserved plant types as they accumulated in an ancestral
peat swamp. Magnification ×0.55. B, Photomicrograph of a
thin section of a small piece of bituminous coal from Illinois photographed
in transmitted light. Magnification approximately ×330.
C, Photomicrograph of a polished surface of a small piece of bituminous
coal from Pennsylvania photographed in reflected light.
Magnification approximately ×250. Parts B and C show some typical
constituents—macerals (plant remains) and minerals—found
in bituminous coals. Macerals are abbreviated as follows: V, vitrinite;
F, fusinite; S, sporinite; and R, resinite. Minerals are abbreviated
as follows: P, pyrite; and C, clay-sized minerals. The scale bar
on parts B and C is 50 micrometers, which is equivalent to about
0.002 inch. The lump of bituminous coal is included to provide a
comparison between what can be seen in a lump of coal and the
wealth of detail in coal that can be seen with high magnification.
The lump of coal is approximately 260 times larger than the chips
of coal represented by either of the photomicrographs.
Photographs and photomicrographs by R.W. Stanton (U.S.
U.S. Department of the Interior, U.S. Geological Survey
For more information, contact Stanley Schweinfurth
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12:28:53 Wed 23 Nov 2016
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