guildite

guildite

[′gil‚dīt]
(mineralogy)
(Cu,Fe)3(Fe,Al)4(SO4)7(OH)4·15H2O A dark-brown mineral composed of a basic hydrated sulfate of copper, iron, and aluminum.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.