lepidomelane

from The Century Dictionary.

• noun A species of the mica group (see mica), of a deep-black color, usually occurring in small, rather inelastic scales. It contains a large amount of iron.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Min.) An iron-potash mica, of a raven-black color, usually found in granitic rocks in small six-sided tables, or as an aggregation of minute opaque scales. See mica.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mineralogy A black iron-potash mica, usually found in granitic rocks in small six-sided tables, or as an aggregation of minute opaque scales.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a mica that is a biotite containing iron