On the Frequent Occurrence of Ankerite in Coal

T. Crook
Scientific and Technical Department, Imperial Institute

Summary: The white layers which occur frequently as infillings of joint-cracks in English coal are miniature mineral-veins. Though averaging less than a millimetre in thickness in ordinary specimens, these veins are in many cases very numerous, and their presence constitutes an important feature in the composition of the coal. As a rule, the dominant mineral is ankerite, which may be normal in composition (i. e. correspond to the formula 2 CaCO3. Fe(Mn)CO3. MgCO3), or may contain a small excess of calcium carbonate, apparently in the form of an isomorphous growth. Calcite also occurs, and is sometimes the dominant mineral. The other associated minerals are iron-pyrites, barytes, zinc-blende, and galena.

Mineralogical Magazine; May 1912 v. 16; no. 75; p. 219-223; DOI: 10.1180/minmag.1912.016.75.06
© 1912, The Mineralogical Society
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