GUILDITE

ˈgilˌdīt noun

( -s )

Etymology: Frank N. Guild died 1939 American mineralogist + English -ite

: a dark chestnut brown mineral (Cu,Fe) 3 (Fe,Al) 4 (SO 4 ) 7 (OH) 4 .15H 2 O that is a basic hydrated sulfate of copper and iron