ˈkränˌsted.ˌīt noun
( -s )
Etymology: German cronstedit, from Baron Axel F. Cronstedt died 1765 Swedish mineralogist + German -it -ite
: a mineral consisting of a black hydrous iron silicate of the chlorite group, crystallizing in hexagonal prisms with perfect basal cleavage, and showing a dark green streak (sp. gr. 3.34-3.35)