lines and dots, and dots
*
Figure 5. — Thin cross section of coal from Illinois No. 6 bed, showing microscopic pyrite globules
(× 200), according to Thiessen
(cropped to square)
illustrating H. F. Yancey and Thomas Fraser. Coal-Washing Investigations : Methods and Tests. Department of Commerce Bulletin 300 (1929)
Michigan copy, digitized February 25, 2009
—
“The pyrite is represented by the black areas, more or less circular, with a streak or smear on one side. The streak is formed during the preparation of the thin section.”
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tags:
dots; lines; streaks; washing
H. F. Yancey and Thomas Fraser. Coal-Washing Investigations (1929)