orthobituminous coal

orthobituminous coal

[¦ȯr·thō·bə′tü·mən·əs ′kōl]
(geology)
Bituminous coal that contains 87-89% carbon, analyzed on a dry, ash-free basis.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.