mustard-seed coal
mustard-seed coal
[′məs·tərd‚sēd ‚kōl] (geology)
Anthracite that will pass through circular holes in a screen which measure 3/64 inch (1.2 millimeter) in diameter.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.